Iran has indicated it is prepared to make concessions on its nuclear programme in talks with the US in return for the lifting of sanctions and recognition of its right to enrich uranium, as it seeks to avert a US attack.

Both sides remain sharply divided -- even over the scope and sequencing of relief from crippling US sanctions -- following two rounds of talks, a senior Iranian official told Reuters.

However, Reuters is reporting for the first time that Iran is offering fresh concessions since their talks ended last week, when the sides appeared far apart and heading closer to military conflict. Analysts say the move suggests Tehran is trying to keep diplomacy alive and stave off a major US strike.

The official said Tehran would seriously consider a combination of sending half of its most highly enriched uranium abroad, diluting the rest and taking part in creating a regional enrichment consortium - an idea periodically raised in years of Iran-linked diplomacy.

Iran would do this in return for US recognition of Iran's right to "peaceful nuclear enrichment" under a deal that would also include lifting economic sanctions, the official said.

In addition, Iran has offered openings for US companies to participate as contractors in Iran's large oil and gas industries, the official said, in negotiations to resolve decades of dispute over Tehran's nuclear activities.

"Within the economic package under negotiation, the United States has also been offered opportunities for serious investment and tangible economic interests in Iran's oil industry," the official said.

The White House did not respond immediately to queries on the issue.

Washington views enrichment inside Iran as a potential pathway to nuclear weapons. Iran denies seeking nuclear weapons and wants its right to enrich uranium to be recognised.

Iran and the United States resumed negotiations earlier this month as the US builds up its military capability in the Middle East. Iran has threatened to strike US bases in the region if it is attacked.

The Iranian official said the most recent discussions underscored the gap between the two sides, but stressed that "the possibility of reaching an interim agreement exists" as negotiations continue.

Iran seeks 'logical timetable' for lifting sanctions

"The last round of talks showed that US ideas regarding the scope and mechanism of sanctions relief differ from Iran's demands. Both sides need to reach a logical timetable for lifting sanctions," the official said.

"This roadmap must be reasonable and based on mutual interests."

Iran's Foreign Minister Abbas Araqchi said on Sunday he expects to meet with US President Donald Trump's special envoy Steve Witkoff in Geneva on Thursday, adding there is still "a good chance" of a diplomatic solution.

Araqchi said on Friday that he expected to have a draft counterproposal ready within days, while Trump said he was considering limited military strikes.

Citing officials on both sides and diplomats across the Gulf and Europe, Reuters reported on Friday that Tehran and Washington are sliding rapidly towards military conflict as hopes fade for a diplomatic settlement.

On Sunday, Witkoff said the president was curious as to why Iran has not yet "capitulated" and agreed to curb its nuclear programme.

"Why, under this pressure, with the amount of seapower and naval power over there, why haven't they come to us and said, 'We profess we don't want a weapon, so here's what we're prepared to do'? And yet it's sort of hard to get them to that place," Witkoff said on Fox News.

Readiness to compromise on nuclear work

Behnam Ben Taleblu, senior director of the Iran program at the Foundation for Defense of Democracies, said Iran's leadership is seeking to buy time via the talks.

"Iran will use that time for various reasons, including to avoid a strike and to harden nuclear, missile, and military facilities," he said.

While rejecting a US demand for "zero enrichment" - a major sticking point in past negotiations - Tehran has signalled its readiness to compromise on its nuclear work.

Washington has also demanded that Iran relinquish its stockpile of highly enriched uranium (HEU). The International Atomic Energy Agency last year estimated that stockpile at more than 440 kg of uranium enriched to up to 60% fissile purity, a small step away from the 90% that is considered weapons grade.

Ali Larijani, a close adviser to Iran's supreme leader, told Al Jazeera TV that Iran was ready to allow extensive IAEA monitoring to prove it is not seeking nuclear weapons.

The agency has been calling on Iran for months to allow for inspection of three nuclear sites that were struck by the US in June last year at the close of a 12-day Israeli bombing campaign. Since then, Tehran has said its uranium enrichment work has stopped.

Satellite images show that Iran has advanced work at a location reportedly bombed by Israel last year, recently building a concrete shield over a new facility at a sensitive military site and covering it in soil, experts say.

Benefits for both sides

Among US demands are restrictions on Tehran's long-range ballistic missiles and an end to its support for regional proxy groups.

Iran has flatly rejected discussing its missiles, while sources have told Reuters, without elaborating, that "the issue of regional proxies is not a red line for Tehran".

Iranian authorities have said that a diplomatic solution would provide economic benefits for both Tehran and Washington.

The Iranian official said Tehran would not hand over control of its oil and mineral resources.

"Ultimately, the US can be an economic partner for Iran, nothing more. American companies can always participate as contractors in Iran's oil and gas fields."