VIENNA, Austria — America has shared new intelligence with the International Atomic Energy Agency that it claims is evidence Iran was trying to make a nuclear weapon, diplomats said yesterday.

One of the diplomats said Washington also gave the IAEA permission to confront Iran with at least some of the information in an attempt to pry details out of the Islamic republic as part of the U.N. nuclear watchdog’s attempts to investigate Iran’s suspicious nuclear past.

The diplomats suggested that such moves by the American administration would be a reflection of Washington’s drive to pressure Iran into acknowledging that it had focused part of its nuclear efforts toward developing a weapons program.

America is leading the push for a third set of U.N. sanctions against Iran. Tehran insists its program is intended only to produce energy and has refused U.N. demands that it suspend its uranium enrichment program — technology that can produce both fuel for nuclear reactors and the fissile material for a bomb.

A recent U.S. intelligence assessment that Iran had a clandestine weapons program but stopped working on it four years ago has hurt Washington’s attempts to have the U.N. Security Council impose a third set of sanctions.

While the Americans have previously declassified and then forwarded intelligence to the IAEA to help its investigations, they do so on a selective basis.

Following Israel’s bombing of a Syrian site late last year, and media reports citing unidentified American officials as saying the target was a nuclear installation, IAEA chief Mohamed ElBaradei turned in vain to America in asking for details on what was struck, said a diplomat who — like others — spoke on condition of anonymity in exchange for divulging confidential information.

Over the past two years, America already has shared material on a laptop computer reportedly smuggled out of Iran. In 2005, American intelligence assessed that information as indicating that Tehran had been working on details of nuclear weapons, including missile trajectories and ideal altitudes for exploding warheads.

After declassification, American intelligence also was forwarded on two other issues: the “Green Salt Project” — a plan America alleges links diverse components of a nuclear weapons program, including uranium enrichment, high explosives testing, and a missile re-entry vehicle — and material in Iran’s possession showing how to mold uranium metal into warhead form.

Two of the diplomats said the material forwarded to the IAEA over the past two weeks expanded on the previous information from the Americans, but had no additional details. Iran is already under two sets of U.N. Security Council sanctions for refusing to suspend uranium enrichment, which it started developing during nearly two decades of covert nuclear activity built on illicit purchases and revealed only five years ago. Since then, IAEA experts have uncovered activities, experiments, and blueprints and materials that point to possible efforts by Iran to create nuclear weapons, even though Tehran insists its nuclear project is peaceful.