Apparently calculated to blunt the threat of new U.N. 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 program.
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 program 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 program," 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 U.N. 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.
Still, a diplomat familiar with Iran's nuclear file described the offer as "the first break in the (nuclear) stalemate in months." Demanding anonymity for discussing the confidential issue, the diplomat told The Associated Press that the invitation to the IAEA to send a team was grounds for optimism that this time the Iranians were serious.
While the key issue remains enrichment, any follow-through by Iran on its decision to share sensitive information with the IAEA could feed sentiment for a compromise that would allow it to retain some elements of its enrichment program while multilateral talks resume on defusing the standoff.
Speaking to reporters Friday after his talks with ElBaradei, Larijani suggested the offer was conditional on reaching a "political understanding" with the EU representative. That was apparent shorthand for a broader deal that would allow for the start of negotiations between Iran and the five permanent council members and Germany on nuclear issues without the present precondition of a complete enrichment freeze.
Multilateral talks with Iran broke off in August 2005 after Tehran rejected an offer of political and economic incentives in exchange for a pledge for long-term suspension and resumed its enrichment activities.
Since then, Iran has repeatedly said an enrichment freeze was out of the question while the six world powers insisted they would accept nothing less as a condition for resuming negotiations.
The Solana-Larijani talks — the third in the past two months — are an attempt to find common ground that would allow such talks to restart.
Because of the standoff over enrichment, the two are skirting the issue and are instead exploring the possibilities of Iran's offer to be more open with the IAEA. On Saturday, Solana described the latest round of talks in Lisbon, Portugal, as "constructive," and said the two planned to meet again in three weeks.
There are recent indications of potential differences on the enrichment issue. U.S. and European diplomats and government employees told the AP last week that Britain, France and Germany are informally debating the idea of a compromise that would call for only a partial freeze — a stance that could put them at odds with Washington.
Germany was supportive, France opposed and Britain noncommittal, they said.
With the United States continuing to insist on a full enrichment freeze, the talks could strain the U.S.-led attempt to show unity on the issue or even push Washington to settle for less than it has been demanding.
For the European allies, a compromise would placate important European Union members Italy and Spain and some smaller countries looking for more flexibility in dealing with Iran.
Secretary of State Condoleezza Rice on Sunday dismissed as "chatter" discussions among U.S. allies about a new approach. But an American official told the AP "there is some truth" to the reports.
The U.S. has allied with Britain, France and Germany in a four-year campaign to contain what they fear are Iranian ambitions to develop nuclear weapons.
The United States' support from permanent Security Council members Britain and France, in particular, has been key.
With permanent members Russia and China only reluctantly backing sanctions and only in weakened form, the loss of European support would leave Washington with the hard choice of either backing away from its insistence on a full enrichment freeze or being isolated.
The compromise being discussed by the Europeans derives from a Swiss proposal under which Iran would not expand its enrichment work in exchange for the Security Council not imposing further sanctions while diplomats pursue a resumption of formal negotiations.