Turkey on Thursday accused Germany of displaying "great political irresponsibility" in stepping up a travel warning for the country after Berlin reacted angrily to Ankara's latest arrests of human rights activists.

"Sending a message... (to Germans) telling them that it's not safe to travel to Turkey is a great political irresponsibility," presidential spokesman Ibrahim Kalin said after Berlin warned it could no longer guarantee its citizens' safety in the country. 

"We do not accept this," he added in televised comments.