Amnesty International activists protest the arrest of rights activists in Turkey | Filippo Monteforte/AFP via Getty Images German human rights activist faces 15 years in jail: Turkish prosecutor Decision could exacerbate already fraught relations between Germany and Turkey.

A Turkish prosecutor on Sunday called for close to a dozen individuals, including German human rights activist Peter Steudtner and Swedish citizen Ali Gharavi, to face up to 15 years in a Turkish prison.

They were charged with "helping an armed terrorist organization" and "becoming a member of an armed terrorist organization," according to CNN Türk.

Steudtner and Gharavi were detained on July 5 after hosting a session on digital security and human rights in Büyükada, an island near Istanbul.

German Chancellor Angela Merkel condemned the arrest as "absolutely unjustified."

"We declare our solidarity with him and all the others arrested ... the German government will do all it can, on all levels, to secure his release," she said at the time, according to Deutsche Welle.

Steudtner's lawyers confirmed the indictment, but were unable to provide further details, German media reported.

The issue of foreign nationals held in Turkey has heightened tensions between Berlin and Ankara in recent weeks. The Turkish government considers Germany's refusal to extradite Turkish nationals accused of involvement in last July's attempted coup to be a major obstacle to repairing relations.

In an interview with German weekly Der Spiegel published Saturday, Turkish foreign minister Mevlüt Çavuşoğlu insisted the justice ministry was independent of the wider government and said he had advocated for Steudtner's case to be expedited.

Çavuşoğlu also called on Germany and Turkey to normalize relations, saying there was "no reason for problems." His comments came after Turkish Prime Minister Binali Yıldırım last week said Turkey should open a “new chapter” with Berlin and “repair” relations.