Turkish prosecutors have ordered the seizure of assets of a Turkish-Iranian gold trader who is testifying in a US trial of a banker accused of violating US sanctions against Iran.
Witness Reza Zarrab earlier told a New York court that Turkish President Recep Tayyip Erdogan had approved his and the defendant's sanctions-breaking deals.
Mr Erdogan has denied that Turkey breached US sanctions on Iran.
The case has strained relations between Ankara and Washington.
On Friday, the Istanbul prosecutor's office said the assets of Mr Zarrab and his family would be confiscated as part of an investigation against the trader, Turkey's state media reported.
They quoted Turkish Prime Minister Binali Yildirim as saying that he hoped Mr Zarrab would "turn back from his mistake" in co-operating with US prosecutors.
Reza Zarrab, 34, is a key witness in the criminal trial of Turkish banker Mehmet Hakan Atilla, whom he allegedly worked with to help Iran launder money.
In his testimony in New York, Mr Zarrab implicated Mr Erdogan in an international money laundering scheme that he and the banker ran between 2010 and 2015, which allegedly allowed Iran access to global markets despite US sanctions.
He said that he was told in 2012 by the then economy minister that Mr Erdogan, who was prime minister at the time, had instructed Turkish banks to participate in the multi-million dollar scheme.