"The talks with the three European countries are aimed at exploring how we can return to the nuclear negotiations," said Araghchi in an interview with state TV.

He said the discussions were "positive and we felt the seriousness ... and (the European parties') desire for a negotiated solution."

"We do not know whether the new US administration intends to return to the negotiations," he added.

Officials from Iran held talks on Monday and Tuesday with counterparts from Britain, France and Germany, known as the E3, which both sides described as "frank and constructive".

The discussions took place a week before US President-elect Donald Trump, who pursued a "maximum pressure" policy of intensified sanctions against Iran during his first term in office, was due to return to the White House.

Iran's Deputy Foreign Minister Kazem Gharibabadi said the discussions revolved around lifting sanctions as well as other issues.

On Tuesday, European Union diplomat Enrique Mora said he held a "constructive meeting" with Iranian officials on "exploring ways for a diplomatic solution to the nuclear issue."

Mora said the talks touched on "Iran's unacceptable military support to Russia."

Ukraine and its allies in many Western capitals have accused Tehran of supplying Moscow with weapons for use in the Russia-Ukraine war.

Iran has repeatedly denied the allegations.

On Tuesday, Araghchi said European countries had "no valid reason for this concern," referring to Iran's policy on Ukraine.

"We are ready to talk about this issue to address the concerns of the Europeans," he added.

The talks were the second round in less than two months, following a meeting in Geneva last November.

In 2015, Iran and world powers -- including France, Britain and Germany -- reached an agreement that eased international sanctions on Tehran in exchange for curbs on its nuclear programme.

But the United States, during Trump's first term in office, unilaterally withdrew from the accord in 2018 and reimposed biting economic sanctions.

Tehran adhered to the deal until Washington's withdrawal, but then began rolling back on its commitments.

Iran has repeatedly expressed willingness to revive the deal.