It is still possible to revive Iran's nuclear deal with world powers, the foreign ministry said Monday, despite long-stalled talks over the 2015 accord.

"There is still a possibility and a chance to resume the implementation of the nuclear deal," ministry spokesman Nasser Kanani said at his weekly news conference.

"Efforts are underway with the European coordinator and other mediators, including the foreign ministries of neighbouring countries, to exchange messages to reach an agreement," he added.

Kanani's remarks come amid on-off talks that have been underway since April 2021 to revive the deal that gave Iran much-needed sanctions relief in return for curbs on its nuclear programme.

The landmark Vienna deal has been in tatters since then US president Donald Trump withdrew from it in 2018 and Iran later backed away from its own commitments.

"Messages between Iran and the United States have been exchanged in New York through the European coordinator (Enrique Mora) and other top officials," Kanani said.

"If the other side, particularly the US government, shows political will, it is possible that a deal will be concluded in a short period," he added.

In a rare concession, Iran allowed a detained Iranian-American to leave the country and released his son from detention, the United Nations confirmed Saturday.

Tehran later said that, following the prisoner release, it was awaiting the unfreezing of about $7 billion in funds held abroad, but Washington denied the two issues were linked.

The European Union had submitted in August a final draft of the text for the agreement, but there remain key sticking points between Tehran and Washington as well as the UN nuclear watchdog.