Iran has given the International Atomic Energy Agency sensitive documents that seem linked to nuclear warhead designs in its efforts to stave off being reported to the U.N. Security Council, diplomats said Tuesday.

The diplomats told The Associated Press that 1 1/2 pages describing how to cast fissile uranium into the hemispherical shape of warheads were given to IAEA inspectors last week.

At the same time, the agency passed to Iran intelligence provided by the United States that suggests Iran has been working on nuclear weapons and asked for its response, said the diplomats, who demanded anonymity in exchange for revealing the confidential information.

Inspectors had seen the document that apparently showed how to mold highly enriched uranium into the core of warheads late last year and it figured in a November report by IAEA head Mohamed ElBaradei.

Initial reports said the agency had been given the documents late last year. But the diplomats said that Tehran handed them over only last week, in a show of cooperation. Iran wanted to head off the growing international consensus that Tehran should be brought before the U.N. Security Council over suspicions its nuclear activities might be a cover for developing weapons, they said.

The document was given to Iran by members of the nuclear black market network, said the IAEA in its November report. It showed how to cast "enriched, natural and depleted uranium metal into hemispherical forms."

Iran has claimed it did not ask for the document but was given it anyway as part of other black market purchases.

Separately, American intelligence revealed last year suggests Tehran's scientists were working on details of nuclear weapons, including missile trajectories and ideal altitudes for exploding warheads.

The diplomats said the United States had recently declassified the information and passed it on to the IAEA, which, in turn, had forwarded it to Iran and asked for an explanation. Washington's cooperation with the agency was part of its attempt to prove that Iran was interested in making weapons, said one of the diplomats, who is familiar with the IAEA probe.

The developments in the fast-moving Iranian nuclear story were revealed just hours after surprising agreement by the five permanent members of the U.N. Security Council that Iran should be hauled before the powerful body over its disputed nuclear program.