ISTANBUL — Turkish prosecutors launched an investigation Saturday of two United States prosecutors involved in putting a Turkish-Iranian businessman on trial for allegedly violating U.S. sanctions against Iran, according to Turkey’s official news agency.

The Istanbul prosecutor’s office said it is investigating Preet Bharara, the former U.S. attorney for the Southern District of New York, and Bharara’s successor, Acting U.S. Attorney Joon H. Kim.

A statement from the Istanbul prosecutor’s office claimed that the sources of the documents and wiretaps being used as evidence in the U.S. case against gold trader Reza Zarrab were unknown and violated international and domestic laws.

Turkey’s official Anadolu Agency published the statement Saturday. The U.S. Attorney’s Office for the Southern District of New York declined to comment.

Zarrab, 34, has been charged in the U.S. for allegedly evading sanctions on Iran. An executive of Turkey’s state-owned bank, Halkbank, also faces charges and is due to appear in court in New York on Nov. 27.

Former Turkish Economy Minister Zafer Caglayan is also among the nine defendants indicted in the case.

Turkish officials allege the case is politically motivated. They have accused Bharara, the former U.S. attorney, of links to a Pennsylvania-based Muslim cleric, Fethullah Gulen, whom the Turkish government blames for a failed July 2016 military coup.

Bharara has vehemently rejected the allegation. Gulen denies involvement in the coup attempt.

The U.S. case was built on work initially performed by Turkish investigators who targeted Zarrab in 2013 in a sweeping corruption scandal that allegedly led to Turkish government officials.

Turkish prosecutors and police involved in the investigation were removed from duty, and charges that resulted from their probe were later dropped.

Since the July 2016 coup attempt, Turkey has arrested more than 50,000 people and fired over 100,000 state workers for alleged links to Gulen’s network.