But US President Donald Trump must first agree there can be no "military option", Araghchi said, and added that Iran would "never accept coercion".

He also insisted the negotiations in Oman would be indirect, contradicting Trump's surprise announcement on Monday that they would be "direct talks".

Trump, who pulled the US out of a 2015 nuclear deal between Iran and world powers during his first term, warned that Iran would be in "great danger" if talks were not successful.

The US and Iran have no diplomatic ties, so last month Trump sent a letter to Iran's supreme leader via the United Arab Emirates. It said he wanted a deal to prevent Iran from acquiring nuclear weapons and to avert possible military strikes by the US and Israel.

Trump disclosed the upcoming talks during a visit to the White House on Monday by Israeli Prime Minister Benjamin Netanyahu, who said on Tuesday that both leaders had agreed "Iran will not have nuclear weapons" and added "the military option" would happen if talks dragged on.

Iran insists its nuclear activities are entirely peaceful and it will never seek to develop or acquire nuclear weapons.

However, Iran has increasingly breached restrictions imposed by the existing nuclear deal, in retaliation for crippling US sanctions reinstated seven years ago, and has stockpiled enough highly-enriched uranium to make several bombs.

The US president told reporters in the Oval Office on Monday that this weekend's meeting in Oman would be "very big".

"I think everybody agrees that doing a deal would be preferable to doing the obvious," Trump said.

But he also warned that it would "be a very bad day for Iran" if the talks were not successful.

In an opinion piece published by the Washington Post on Tuesday, Iran's foreign minister declared that it was "ready to engage in earnest and with a view to seal a deal".

"We will meet in Oman on Saturday for indirect negotiations. It is as much an opportunity as it is a test," Araghchi said.

Iran harboured "serious doubts" about the sincerity of the US government's intentions, he noted, citing the "maximum pressure" campaign of sanctions that Trump restored soon after starting his second term.

"To move forward today, we first need to agree that there can be no 'military option', let alone a 'military solution'," he said.

"The proud Iranian nation, whose strength my government relies on for real deterrence, will never accept coercion and imposition."

Araghchi insisted there was no evidence that Iran had violated its commitment not to seek nuclear weapons, but also acknowledged that "there may exist possible concerns about our nuclear programme".

"We are willing to clarify our peaceful intent and take the necessary measures to allay any possible concern. For its part, the United States can show that it is serious about diplomacy by showing that it will stick to any deal it makes. If we are shown respect, we will reciprocate it."

"The ball is now in America's court," he added.