US negotiators are seeking to persuade Iran to abandon plans to charge tolls in the Strait of Hormuz, arguing Tehran could earn far more by following through with nuclear concessions, Axios reported on July 1.

The effort points to the fragility of a memorandum of understanding signed two weeks ago, which gave the two sides 60 days to negotiate a final deal on Iran's nuclear programme, with substantive talks stalled over disagreements about the strait.

The technical talks are taking place in Doha, though it remains unclear whether the US is meeting Iran directly or indirectly through Qatari and Pakistani mediators. Iran has insisted it is not meeting the US while disputes over implementation of the MOU continue.

"We have reached an understanding that we will keep things quiet for the coming week, so progress on all aspects of the MOU can be worked on in a productive environment, without missiles flying," a US official told Axios, adding that the president had made clear the US would respond to any Iranian fire with strikes on targets degrading its position in the strait.

US Vice President JD Vance said the US technical team was meeting the Iranians, Qataris and others in Doha, describing the talks as early but going well.

In response to Iran's plan to charge tolls after the 60-day period expires, the US message was to "think bigger," the official said, claiming the sums Iran could generate from developing and selling oil once sanctions are lifted would be far more valuable than charging a toll.

The sides reached an understanding on the release of a first batch of frozen Iranian funds held by Qatar, Al Arabiya reported. A regional source said $3bn would be made available to the Iranian central bank for humanitarian goods, though US officials denied an agreement had been reached.

Iranian negotiators also raised concern over Israel's continued presence in Lebanon, in apparent violation of the MOU. A regional source said US negotiators told Iran that Washington had coaxed Israel to withdraw from two areas of south Lebanon, with further pull-backs to follow if implemented.