NEW YORK (Reuters) - Lawyers for a Turkish banker on trial in New York on charges that he helped Iran evade U.S. sanctions asked a judge on Wednesday to declare a mistrial, saying testimony by a former Turkish police investigator should not have been allowed in court.

FILE PHOTO: Mehmet Hakan Atilla (R), a deputy general manager of Halkbank, sits with lawyer Victor Rocco as he appears in Manhattan federal court in New York, U.S., April 24, 2017. REUTERS/Jane Rosenberg

The lawyers for Mehmet Hakan Atilla, an executive at Turkey’s majority state-owned Halkbank, said the jury had been “tainted” after hearing Huseyin Korkmaz testify in Manhattan federal court this week that he feared he would be tortured if he returned to Turkey, where he led an investigation involving Turkish officials, Atilla and others.

“Associating the defendant with the specter of mindless and cruel political violence at the hands of his government-based alleged co-conspirators is almost guaranteed to inflame the jury against the defendant,” the lawyers said.

Assistant U.S. Attorney Michael Lockard said in court late on Wednesday that prosecutors would file a response on Thursday.

Prosecutors have accused Atilla, 47, of working with Turkish-Iranian gold trader Reza Zarrab and others to help Iran evade U.S. sanctions through fraudulent gold and food transactions.

Atilla has pleaded not guilty. Zarrab, 34, pleaded guilty and testified for U.S. prosecutors.

The case has strained ties between the United States and Turkey. A spokesman for the Turkish government has called the case a “plot against Turkey.”

Korkmaz testified that while investigating claims that Zarrab was laundering money in 2012 and 2013, he uncovered evidence that Turkish President Recep Tayyip Erdogan, then prime minister, and Zafer Caglayan, then economy minister, were working with Zarrab.

Korkmaz also said that Halkbank’s then-general manager, Suleyman Aslan, took bribes from Zarrab, but that there was no evidence Atilla took bribes.

Caglayan, Aslan and a spokesman for Erdogan could not be reached for comment.

Korkmaz said he was reassigned after his investigation became public in 2013, and that in 2014 he was arrested and jailed.

He said he fled Turkey in 2016, soon after he was released. Korkmaz testified on Tuesday that the U.S. Federal Bureau of Investigation had given him $50,000 in financial assistance after he came to the United States.

Turkey’s foreign minister, Mevlut Cavusoglu, said in November that U.S.-based cleric Fethullah Gulen, blamed by Ankara for last year’s failed coup, was behind both the U.S. case and the earlier Turkish investigation.

While being questioned by one of Atilla’s lawyers on Wednesday, Korkmaz denied being associated with Gulen.

On Wednesday, state-run Anadolu Agency said that Turkish police had summoned an FBI official over statements Korkmaz made in court.

U.S. State Department spokeswoman Heather Nauert confirmed that an FBI attache at the U.S. Embassy “had been brought in to the Turkish ministry.” She provided no details.