A proposed deal between Iran and Oman would give Tehran control over ships entering the Gulf through the Strait of Hormuz, a senior Iranian source and two regional officials told Reuters, in one of the biggest concessions yet to Iran.
Despite the apparent step towards yielding to Iranian demands, the sources pushed back against assertions by US President Donald Trump that a deal reopening the strait was imminent.
Iran later reported "significant progress" in the talks with Oman over transit routes, saying both inward and outward journeys would pass through Iranian waters.
U.S. officials have repeatedly said that they would never accept any arrangement that lets Iran control access to the world's most important trade route for energy supplies.
At a regular briefing in New York, deputy UN spokesperson Farhan Haq said the United Nations had received no first-hand information about a possible reopening of the Strait of Hormuz, but added: "We certainly encourage the parties to move forward with any effort to have a negotiated solution to the issue."
An agreement that gives Iran any control over access to the strait would mean the war launched by the United States and Israel had resulted in a major shift in the balance of regional power in Tehran's favor. Before the war, the strait was freely open to all ships with no fees.
But Trump, who initially said "Operation Epic Fury" would end in Iran's "unconditional surrender" with him approving the choice of its leader, has been under pressure to find a way out of a war US voters now oppose two-to-one.
According to the senior Iranian official, Iran is seeking fees of between 5% and 7% of the price of cargoes from ships using the strait. Oman is discussing smaller fees of around 3%, while Washington wants no fees at all.
Making any fees voluntary, at least nominally, could be a way out of the impasse, although an implied threat of Iranian attacks could mean shippers would be unlikely to risk transit without paying.