Vienna, Austria ? Acting on a request from Iran, the International Atomic Energy Agency said Monday it will send a team to Tehran to work jointly on a plan meant to clear up suspicions about the Islamic republic’s nuclear activities.

The invitation, conveyed Sunday by a senior Iranian envoy and made public Monday by the agency, was portrayed by some diplomats as a positive step in IAEA attempts to learn more about past activities that could point toward a weapons program.

But the U.S. said it was skeptical.

“I don’t think Iran’s track record is particularly noteworthy or particularly likely to give me or anyone else confidence that anything will come of these discussions,” State De-partment spokesman Tom Casey said in Washington.

The invitation was linked to a recent Iranian offer to stop stonewalling the agency in its probe of more than two decades of Iranian nuclear activities – clandestine until 2002 when they were revealed by a dissident group.

If followed through, it could generate international good will that might blunt the threat of new U.N. sanctions and increase pressure on the U.S. and its closest allies to compromise on their insistence for a full enrichment freeze.

Besides demanding such a freeze – and answers to the IAEA’s questions – the Security Council wants Iran to stop building a plutonium-producing reactor.

The country’s refusal to provide answers originally prompted the council to get involved. Since December, it has imposed two sets of sanctions and has begun informal consultations on new penalties.

Iran says it wants to develop enrichment only to generate power. But its stonewalling of the IAEA has heightened suspicions that it wants to enrich uranium for use in warheads.

Meeting Sunday with IAEA head Mohamed ElBaradei, chief Iranian nuclear negotiator Ali Larijani “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.

Iran’s offer to deal with outstanding questions was also the focus of talks Saturday between Larijani and top EU foreign policy envoy Javier Solana.

A European diplomat said the decision to invite an IAEA delegation was reached at those talks and that Larijani had asked for 120 days to clear up ambiguities – a span that Solana rejected as too long.