"I am aware that some businessmen are attempting to place their assets overseas. I call on the government not to authorise any such moves, because these are acts of treason," Erdogan said in televised comments to party members in the eastern town on Mus.
The Turkish president did not name names, but his comments came two days after Turkish prosecutors ordered the seizure of assets of a gold trader testifying in a New York trial against a Turkish banker accused of violating US sanctions against Iran.
The Hurriyet daily said the order affected Zarrab and 22 others, including his daughter with Turkish pop star Ebru Gundes.
The trader on Thursday implied in testimony that Erdogan knew how he and defendant Mehmet Hakan Atilla, deputy chief executive of Turkish lender Halkbank, had dodged sanctions.
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He told the court he was informed that in 2012, then prime minister Erdogan and then treasury minister Ali Babacan had given "instructions" for two other Turkish public banks, Vakif and Ziraat, to take part in the scheme.
Ankara has accused the trial of being a "conspiracy" and suggested the American judiciary is seeking to corner Turkey politically and economically.
Erdogan today described the ongoing trial in the United States as an "attempt at blackmail" to which "we will not submit".