ANKARA (Reuters) - Comments by German officials regarding Turkey’s arrest of six human rights activists, including a German citizen, were unacceptable and amounted to interference in the judiciary, the Turkish Foreign Ministry said on Thursday.

Germany raised the possibility on Wednesday of suspending European Union aid payments to Turkey after summoning Ankara’s ambassador to Berlin to protest over the arrest of the six, including Amnesty International’s Turkey head Idil Eser.

German citizen Peter Steudtner was also among those jailed pending trial on terrorism charges, which Berlin has labeled “absurd”, in a move which further escalated tensions between the NATO allies.

“There was direct interference in the Turkish judiciary and comments used which overstepped the mark,” Turkey’s foreign ministry said, referring to comments by the German government and foreign ministry spokesmen.

“The comments again show the double standards in their approach to the law of those who prevent terrorists being brought to justice while embracing members of terrorist groups which target our country,” the ministry said.

The six rights activists are among 50,000 jailed pending trial in Turkey in a crackdown that followed an attempted coup a year ago.