ANKARA, July 21 -- Turkey has accused Germany of harboring "terrorists" following German threats to slap sanctions and to issue travel advisory for its citizens amid a violent escalating row over Turkey's arrest of human rights activists.

Germany told its citizens on Thursday to exercise caution when traveling to Turkey and warned that it might cut off export insurance guarantees and other forms of economic cooperation, the latest step in the deterioration of relations between the two key NATO allies and close economic partners.

German Foreign Minister Sigmar Gabriel cut short a vacation to denounce on Thursday the arrests in Turkey of several human rights activists, including a German citizen, Peter Steudtner, a representative of Amnesty International. "We are reorienting our policy toward Turkey," Gabriel said.

Turkey's Foreign Minister Mevlut Cavusoglu called Gabriel's remarks "threats and blackmail," which were not "worthy of a serious country." He accused Germany of harboring terrorists by "providing shelter" to the Kurdistan Workers' Party and to the followers of the self-exiled Muslim cleric Fethullah Gulen, accused by Ankara of plotting a failed coup attempt last July.

The harsh exchange was the latest step in the worsening of relations between two countries with deep economic and demographic ties. Even before the coup attempt in Turkey last year, President Recep Tayyip Erdogan had begun to disturb many German officials and also other western leaders.

Several dozens of military personnel and diplomats applied for asylum in Germany while Turkey demanded, in vain, for their extradition. Germany as well as some other EU countries also infuriated Erdogan for refusing him to hold rallies for the Turkish diaspora ahead of the crucial April constitutional referendum that granted the Turkish head of state extensive executive powers.

The tensions came to a new head this week after the Turkish authorities decided to hold Steudtner under arrest. He was detained on July 5 with five others, including Amnesty International's Turkey director, in a raid on a hotel where they were attending a digital security workshop. The Turkish authorities have accused them of having links to terrorist groups.

"The case of Peter Steudtner shows that German citizens are no longer safe from arbitrary arrests," Gabriel said. Berlin said nine other German citizens, including two journalists, Deniz Yucel and Mesale Tolu, were being held by Turkey.

Gabriel said the Germans had been accused without evidence. He cited their detentions as "examples of the absurd accusations of terror propaganda that obviously are only meant to serve to silence every critical voice in Turkey.

The German government will consider "further measures" in the coming weeks, after discussing the future of financial aid for Ankara with its EU partners, in the context of the long-stalled talks on Turkey potentially joining the bloc, Gabriel said.

Berlin also said it would review Turkish applications for arms projects.

In Turkey, ministers lashed back, with Cavusoglu accusing Germany of maintaining an "unacceptable, one-sided" attitude. He said that threats and blackmail would find no answers in Turkey, but also maintained a more mellow tone pointing out that the two countries needed to focus on their long-term goals.

For his part, Turkey's presidential spokesman Ibrahim Kalin slammed Germany as "great political irresponsibility" in stepping up its travel warning. He pointed out that millions of Germans were fully safe visiting Turkey and those under judicial prosecution were only a handful of German nationals.

President Erdogan told his country in a speech on Friday to "pull itself together," and said that "Germany cannot scare Turkey with threats."

Erdogan also strongly denied reports that some German companies were investigated by Turkish judges for suspected terrorist links.

The German Bild newspaper asked in a rather cynical mood if "Erdogan would also arrest (German) tourists" in Turkey, which is a major destination of millions of Europeans each summer.

Some 3 million Turks live in Germany for many decades as they immigrated as workers, and trade volume is also big between the two countries.

"This is probably the biggest crisis in modern times between the two countries," said Hakan Celik, a political commentator on cnn Turk news channel.

"Let's hope that the countries solve this crisis with dialogue and common sense," he said, adding that there was a lot at stake, namely commercial ties, in this row.

Turkey launched a massive crackdown against Gulen followers but also all kind of opposition circles, in which some 50,000 people have been detained and 150,000 sacked or suspended from the judiciary to academia.

Erdogan argues that this move and the state of emergency are both essential.

This uNPRecedented purge has been criticized by Berlin who refused to extradite suspected coup plotters.

At the beginning of July, Germany began withdrawing its forces from NATO's Incirlik Air Base in southern Turkey, after Ankara refused German parliament members from visiting them.

ANKARA, July 21 -- Turkey has accused Germany of harboring "terrorists" following German threats to slap sanctions and to issue travel advisory for its citizens amid a violent escalating row over Turkey's arrest of human rights activists.

Germany told its citizens on Thursday to exercise caution when traveling to Turkey and warned that it might cut off export insurance guarantees and other forms of economic cooperation, the latest step in the deterioration of relations between the two key NATO allies and close economic partners.

German Foreign Minister Sigmar Gabriel cut short a vacation to denounce on Thursday the arrests in Turkey of several human rights activists, including a German citizen, Peter Steudtner, a representative of Amnesty International. "We are reorienting our policy toward Turkey," Gabriel said.

Turkey's Foreign Minister Mevlut Cavusoglu called Gabriel's remarks "threats and blackmail," which were not "worthy of a serious country." He accused Germany of harboring terrorists by "providing shelter" to the Kurdistan Workers' Party and to the followers of the self-exiled Muslim cleric Fethullah Gulen, accused by Ankara of plotting a failed coup attempt last July.

The harsh exchange was the latest step in the worsening of relations between two countries with deep economic and demographic ties. Even before the coup attempt in Turkey last year, President Recep Tayyip Erdogan had begun to disturb many German officials and also other western leaders.

Several dozens of military personnel and diplomats applied for asylum in Germany while Turkey demanded, in vain, for their extradition. Germany as well as some other EU countries also infuriated Erdogan for refusing him to hold rallies for the Turkish diaspora ahead of the crucial April constitutional referendum that granted the Turkish head of state extensive executive powers.

The tensions came to a new head this week after the Turkish authorities decided to hold Steudtner under arrest. He was detained on July 5 with five others, including Amnesty International's Turkey director, in a raid on a hotel where they were attending a digital security workshop. The Turkish authorities have accused them of having links to terrorist groups.

"The case of Peter Steudtner shows that German citizens are no longer safe from arbitrary arrests," Gabriel said. Berlin said nine other German citizens, including two journalists, Deniz Yucel and Mesale Tolu, were being held by Turkey.

Gabriel said the Germans had been accused without evidence. He cited their detentions as "examples of the absurd accusations of terror propaganda that obviously are only meant to serve to silence every critical voice in Turkey.

The German government will consider "further measures" in the coming weeks, after discussing the future of financial aid for Ankara with its EU partners, in the context of the long-stalled talks on Turkey potentially joining the bloc, Gabriel said.

Berlin also said it would review Turkish applications for arms projects.

In Turkey, ministers lashed back, with Cavusoglu accusing Germany of maintaining an "unacceptable, one-sided" attitude. He said that threats and blackmail would find no answers in Turkey, but also maintained a more mellow tone pointing out that the two countries needed to focus on their long-term goals.

For his part, Turkey's presidential spokesman Ibrahim Kalin slammed Germany as "great political irresponsibility" in stepping up its travel warning. He pointed out that millions of Germans were fully safe visiting Turkey and those under judicial prosecution were only a handful of German nationals.

President Erdogan told his country in a speech on Friday to "pull itself together," and said that "Germany cannot scare Turkey with threats."

Erdogan also strongly denied reports that some German companies were investigated by Turkish judges for suspected terrorist links.

The German Bild newspaper asked in a rather cynical mood if "Erdogan would also arrest (German) tourists" in Turkey, which is a major destination of millions of Europeans each summer.

Some 3 million Turks live in Germany for many decades as they immigrated as workers, and trade volume is also big between the two countries.

"This is probably the biggest crisis in modern times between the two countries," said Hakan Celik, a political commentator on cnn Turk news channel.

"Let's hope that the countries solve this crisis with dialogue and common sense," he said, adding that there was a lot at stake, namely commercial ties, in this row.

Turkey launched a massive crackdown against Gulen followers but also all kind of opposition circles, in which some 50,000 people have been detained and 150,000 sacked or suspended from the judiciary to academia.

Erdogan argues that this move and the state of emergency are both essential.

This uNPRecedented purge has been criticized by Berlin who refused to extradite suspected coup plotters.

At the beginning of July, Germany began withdrawing its forces from NATO's Incirlik Air Base in southern Turkey, after Ankara refused German parliament members from visiting them.