“We hope Iran takes this opportunity to co-operate with the IAEA in good faith towards closing these outstanding matters,” a joint statement from the UK, US, Germany and France said.
The nuclear watchdog's board of governors passed a resolution on Thursday calling for Iran’s co-operation during a long-running impasse over uranium particles found at three undeclared locations.
British Foreign Secretary James Cleverly will accuse Iran of spreading “bloodshed and destruction” when he addresses the Manama Dialogue in Bahrain on Saturday.
The IAEA has said it cannot be sure that Iran's nuclear activities are peaceful until it receives a satisfactory explanation, it said.
The four nations on Friday urged Iran to “take the actions specified without delay”.
“This resolution was adopted in response to Iran’s insufficient co-operation with the IAEA on serious and outstanding issues relating to Iran’s legal obligations under its Non-Proliferation Treaty (NPT) Safeguards Agreement,” the statement read.
“The board has sent a clear message that it is essential and urgent that Iran fulfils its NPT-required safeguards obligations and take the actions specified without delay.
“Iran must provide technically credible explanations for the presence of uranium particles identified at three undeclared locations in Iran and clarify the whereabouts of the related nuclear material and/or contaminated equipment.
“The resolution reaffirms the board’s unwavering support for the IAEA’s long-standing efforts with Iran to resolve these critical matters.
“As we have made clear, if Iran does this and the director general is able to report that the unresolved safeguards issues are no longer outstanding, the board could then close its consideration of this matter.
“We hope Iran takes this opportunity to co-operate with the IAEA in good faith towards closing these outstanding matters so that no further board action on these issues will be necessary.”
During his address to the Manama Dialogue security conference, Mr Cleverly will warn that Iranian weapons are threatening security in the Middle East and beyond.
“Iranian-supplied weapons threaten the entire region,” he will say, according to advance extracts of his speech.
“Today, Iran’s nuclear programme is more advanced than ever before, and the regime has resorted to selling Russia the armed drones that are killing civilians in Ukraine.
“Britain is determined to work alongside our friends to counter the Iranian threat, interdict the smuggling of conventional arms and prevent the regime from acquiring a nuclear weapons capability.”
The resolution adopted by the IAEA's 35-nation board was carried by 26 votes in favour versus two against, with five abstentions and two countries absent, diplomats said.
Russia and China voted against it. Tehran has criticised the resolution, warning it could affect co-operation with the IAEA.
The impasse over the agency's probe comes as wider talks to revive the key 2015 nuclear deal are stalled.
The agreement Iran reached with Britain, China, France, Germany, Russia and the US gave Tehran relief from sanctions in return for guarantees it would not develop an atomic weapon.
The deal collapsed after Washington's unilateral withdrawal in 2018 under then-president Donald Trump.