Turkey revokes Istanbul operating licence of Iran's Bank Mellat over financial stability risks

Regulatory decision in Istanbul

Turkey's Banking Regulation and Supervision Agency (BDDK) revoked the operating licence of the Istanbul central branch of Iranian lender Bank Mellat. The regulatory ruling, formally adopted on 18 September 2026, appeared in the Turkish Official Gazette on Saturday, 19 September 2026. The official announcement confirmed the immediate withdrawal of operating permissions for Bank Mellat Merkezi Tahran İstanbul Türkiye Merkez Şubesi.

The watchdog based its intervention on Article 71, paragraph 1, subparagraph (b) of Banking Law No. 5411. Under this specific statutory clause, the agency holds the legal authority to revoke an operating licence or transfer an institution to the Savings Deposit Insurance Fund (TMSF). Regulators apply the provision when supervision audits establish that continued banking activity poses a danger to the rights of depositors and participation fund owners, or threatens the security and stability of the national financial architecture.

It has been decided to revoke the operating licence of Bank Mellat, Head Office in Tehran, Istanbul Turkey Central Branch.

International sanctions background

Headquartered in Tehran, Bank Mellat is one of Iran's largest commercial lenders and has faced sustained measures from the United States, the European Union, and the United Kingdom. Western governments previously imposed sanctions over claims that Iranian financial institutions supported covert efforts to develop nuclear weapons under civil energy programs, as well as providing direct financial assistance to the Iranian state.

Those restrictions were temporarily removed under the 2015 joint nuclear agreement signed between Tehran and global powers. The sanctions relief ceased in May 2018 when the United States withdrew unilaterally from the pact under President Donald Trump and restored sweeping economic penalties against Iran. In 2019, Washington and Gulf partners applied further sanctions against Bank Mellat after identifying it as one of 25 corporate entities connected to the Islamic Revolutionary Guard Corps (IRGC).

US enforcement on regional financial channels

The Turkish regulator's ruling arrived two weeks after the United States Treasury Department announced sanctions against Turkish financial institutions over suspected Iranian links. On 4 September 2026, the US Treasury sanctioned Istanbul-based investment firm Golden Global Yatırım Bankası Anonim Şirketi (Golden Global Bank) alongside two corporate subsidiaries, Golden Global Portföy Yönetimi and Golden Global Varlık Kiralama.

American authorities stated that Golden Global Bank facilitated tens of millions of dollars in financial transactions for the Islamic Revolutionary Guard Corps-Qods Force (IRGC-QF) and provided Iranian authorities with banking channels to transfer sovereign capital across international borders. The US measures froze all American-held assets linked to the institutions and prohibited commercial transactions with the designated entities. Golden Global Bank rejected the allegations, while Washington introduced additional restrictions against Iranian carrier Mahan Air shortly afterward.

Regulatory scope and systemic oversight

The official BDDK notice published in the Turkish Official Gazette contained no explicit mention of American sanction programs, nor did it cite specific operational infractions by the Iranian lender. The legal text adhered strictly to domestic banking provisions regarding systemic resilience and depositor protection.

The closure of the Istanbul central branch restricts the financial channels available to Iranian institutions operating in third-country markets. Under Turkey's Banking Law, the BDDK retains oversight authority to terminate branch permissions when financial audits indicate operational exposure to broader systemic risks.