Oil residue lines the shore near fishing boats on Qeshm Island, Iran, on Thursday. AMIRHOSEIN KHORGOOI/AP

The United States is launching a financial campaign to economically isolate Iran, with US Treasury Secretary Scott Bessent saying Washington would apply unprecedented economic measures on Tehran as their differences over the Strait of Hormuz persist.

Conflicting claims by Iran and the US over one of the world's critical shipping lanes have kept Tehran and Washington apart, as mediators have struggled to break the stalemate since both sides signed the Islamabad Memorandum of Understanding in June.

Bessent said in his interview with US-based media Newsmax on Thursday that the measures would combine economic isolation with the continued blockade of the Strait of Hormuz to prevent anything from entering or exiting Iranian ports.

"Watch this space for more announcements," Bessent said, adding that the US is "going to apply measures like have never been seen in the history of economic isolation".