VIENNA, June 25: Iran has invited the International Atomic Energy Agency to send a team to agree how to resolve longstanding IAEA questions about Tehran’s atomic programme, the UN watchdog said on Monday.

Tehran’s conciliatory gesture came as the United States, Britain, Russia, France, Germany and China began discussing a third, harsher batch of UN sanctions against Tehran for refusing to suspend nuclear enrichment-related activities.

Iran's chief negotiator Ali Larijani, who agreed a “plan of action” for transparency with IAEA director Mohamed ElBaradei in talks on Friday, returned to see ElBaradei on Sunday and issued the invitation, the agency said in a statement.

Olli Heinonen, the IAEA's global head of inspectors, was expected to lead the team after his return from North Korea, where he will begin a five-day visit on Tuesday to lay groundwork for Pyongyang's promised nuclear disarmament.

“This (new deal) is the first break in a stalemate that has been going on since then on allowing the IAEA to resolve these remaining mysteries,” said a Vienna diplomat close to the IAEA.

The Larijani-ElBaradei deal calls for the IAEA and Tehran to agree within two months what steps will be needed to “let the IAEA get to the bottom of the issues”, the diplomat said.

This would likely entail access for IAEA inspectors to Iranian sites, documents and officials at the centre of indications of past covert activity with military links.

Iran has long conditioned full transparency on the UN Security Council first returning authority over its file to the IAEA. Western powers reject such a concession, saying dropping sanctions options would relieve Iran of pressure to cooperate.

The diplomat said Larijani did not repeat that demand in his meetings with ElBaradei. But, asked whether wider, stiffer sanctions now being contemplated could unravel the IAEA-Iran deal, the diplomat said, “Surely”.

Russia, one of five powers with a Security Council veto, has hinted at disagreement with a US thrust for more sanctions soon by saying it will back them only once the IAEA declared all possibilities to resolve its questions had been exhausted.—Reuters