Iran has blacklisted 45 tankers for allegedly violating its requirements for crossing the Strait of Hormuz, escalating pressure on shipping using the strategically important waterway.

The Persian Gulf Strait Authority, a newly established Iranian body responsible for managing the strait, announced the restrictions in a post on X. According to the authority, the named vessels could be fined or detained, while their cargoes could be confiscated.

Iran also warned that vessels conducting ship-to-ship cargo transfers with any of the listed tankers could themselves be added to the blacklist. Cargo owners undertaking Gulf-related voyages were advised to consult an updated list of ships classified as non-compliant.

The authority did not specify which transit requirements the 45 vessels had allegedly breached. Iran has previously said that shipowners should obtain its clearance before passing through the Strait of Hormuz and should pay for security and other services.

The restricted vessels cover several tanker segments, including very large crude carriers, liquefied natural gas carriers, liquefied petroleum gas tankers and clean petroleum product vessels.

The list includes ships connected with ADNOC Logistics and Shipping, its Navig8 Tankers subsidiary, and Saudi Arabian national shipping company Bahri. Vessels owned by Klaveness Ship Management, Stolt Tankers and South Korea’s Sinokor were also named. ADNOC declined to comment, while other shipping companies did not immediately respond to requests for comment cited in the source report.

Among the vessels appearing on the list are Kiku, Mubaraz, Minoan Pioneer, Hafeet, Al Rekayyat, Wedyan, Cyprus Prosperity, Al Rawdah, Rasheeda, Lila Vadinar, GFS Galaxy, Stolt Magnesium, Navig8 Messi, Singapore Prosperity, GasLog Shanghai, Nissos Kea, Rotterdam Energy and Marigold LNG. The authority provided IMO numbers for the listed ships.

Owners seeking to have a vessel removed from the non-compliance list must submit a request and relevant explanations to the Iranian maritime authorities, according to the announcement.

The measure comes amid heightened tensions involving Iran and the United States. The source report said the US has imposed a naval blockade targeting Iran-related shipping, while US-coordinated tanker movements through the strait have helped restore some disrupted exports.

Before the conflict affected tanker traffic, the Gulf supplied about 20% of global daily crude oil and LNG volumes. US Secretary of Energy Chris Wright said the seven-day average of oil leaving the Strait of Hormuz had risen above 8 million barrels per day.