The Supreme Court had set a Monday deadline for Halkbank to file a petition appealing the October 2024 ruling by the 2nd US Circuit Court of Appeals in Manhattan, which cleared the way for the prosecution.
In a letter to the appeals court, Halkbank's lawyer Robert Cary confirmed the petition had been filed, though it was not immediately available on the Supreme Court's website.
Halkbank has pleaded not guilty to charges of fraud, money laundering, and conspiracy, accused of using money servicers and front companies in Iran, Turkey, and the United Arab Emirates to circumvent US sanctions.
US prosecutors allege that Halkbank facilitated the secret transfer of $20 billion in restricted Iranian funds, converted oil revenue into gold and cash for Iranian interests, and fabricated documentation for food shipments to justify oil proceeds transfers.
The case, initiated in 2019, has strained relations between the US and Turkey, with Turkish President Tayyip Erdogan denouncing it as an "unlawful, ugly" step.
However, both Erdogan and US President Donald Trump reported a productive phone call on Monday, with mutual invitations to visit their respective countries.
It is Halkbank's second appeal to the Supreme Court. In 2023, the court ruled that while the Foreign Sovereign Immunities Act of 1976 shields foreign countries from civil liability, it does not extend to criminal cases.
The Supreme Court then instructed the 2nd Circuit to further examine whether common law immunity protected Halkbank, leading to the October ruling that the bank could be prosecuted.
Trump maintains his so-called maximum pressure campaign against Iran, threatening secondary sanctions and targeting those aiding sanctions evasion, while indirect nuclear talks between the US and Iran continue.