Turkish President Recep Tayyip Erdogan has called on Germany to extradite supporters of a US-based Muslim cleric whom he blames for an attempted coup.
Speaking in Berlin, he said Germany should designate followers of Fethullah Gulen as terrorists.
Chancellor Angela Merkel told a news conference that Germany needed more evidence against the group.
She also urged Turkey to quickly resolve cases of German citizens imprisoned in Turkey.
"I have pressed for it and will continue to do so, that these cases can be solved quickly," she said.
Germany welcomes Erdogan through gritted teeth
Who are the Gulenists?
In depth: Erdogan's Turkey
Mr Erdogan is on a three-day state visit to Germany try to improve strained ties between the two Nato allies. Relations have soured since Mr Erdogan launched a crackdown following the 2016 failed military coup.
Heavy security is in place in Berlin, where police expect street protests by pro- and anti-Erdogan groups. Germany is home to three million ethnic Turks.
What did Erdogan say?
The Turkish president said there were hundreds of members of Mr Gulen's network - which he described as a terror organisation - in Germany.
"I believe in apprehending whoever, wherever, and handing them to Turkey," he told the sometimes tense news