Apparently calculated to blunt the threat of new UN sanctions, the move could increase pressure on the United States and its closest allies to reconsider their insistence that Iran fully freeze all uranium enrichment activities.

Such a freeze is being called for by the Security Council along with other demands, including a requirement that Iran stop stonewalling the Vienna-based nuclear watchdog agency and answer questions about activities that could be linked to a weapons programme.

Tehran's refusal to meet agency requests for answers originally prompted the council call for a stop to all enrichment activities. Since December, the council has imposed two sets of sanctions and has begun informal consultations on new penalties because of Tehran's nuclear defiance.

Iran says it wants to develop a full enrichment programme only to generate power and says it has the right to do so under the Nuclear Nonproliferation Treaty. But its refusal to come up with the answers to IAEA questions has heightened suspicions its real plan is to enrich uranium to weapons grade, for use as the fissile core of warheads.

The offer came Sunday during a meeting with IAEA head Mohamed ElBaradei, when Ali Larijani, Tehran's chief nuclear negotiator, "invited the IAEA to send a team to Tehran to develop an action plan for resolving outstanding issues related to Iran's past nuclear programme," said agency spokeswoman Melissa Fleming

"The IAEA intends to send a team as early as practicable," she said in a statement

The talks Sunday were apparently agreed upon on short notice and came just a day after Larijani met with top EU foreign policy envoy Javier Solana for talks believed to have focused on Tehran's recent offer to deal with outstanding questions.

Larijani and ElBaradei had already met Friday and the IAEA chief said afterward that the Islamic republic was ready to follow up on that offer by working out a concrete timetable with his agency's experts on coming up with the answers sought by the UN nuclear agency.

Iran has said before that it was ready to cooperate with the IAEA on the issue of unexplained past activities that could be linked to a nuclear weapons program but has yet to deliver.