Iran's Supreme Leader Ayatollah Ali Khamenei said yesterday he was satisfied with talks with arch-foe the United States but warned they could ultimately prove fruitless.

Tehran and Washington are due to meet again in Muscat on Saturday, a week after top officials held the highest-level talks since the landmark 2015 nuclear accord collapsed.

US President Donald Trump, who pulled out of the deal during his first term, revived his "maximum pressure" sanctions campaign after returning to office in January.

In March, he sent a letter to Khamenei urging talks and warning of possible military action if Iran refused. Saturday's talks were "well carried out in the first steps", Khamenei said, quoted by state television. "Of course, we are very pessimistic about the other side, but we are optimistic about our own capabilities."

But he added that "the negotiations may or may not yield results".