"It is essential for the integrity and credibility of the inspection process that we are able to bring these issues to a close within the next few months and provide the international community with the assurances it urgently seeks regarding Iran's nuclear activities," El Baradei told the board of the International Atomic Energy Agency (IAEA), of which he is director general.

"The central question is whether Iran's uranium enrichment activities have been fully declared," ElBaradei said, according to a copy of his speech to the 35-nation board meeting in Vienna.

Elbaradei said the IAEA has been aware of "Iran's undeclared nuclear program" for almost two years but had been kept from getting to the bottom of it due to "less than satisfactory" cooperation from Iran.

Tehran needed to be "proactive and fully transparent" from now on as "we can not go on forever," ElBaradei said.

The United States accuses Iran of secretly trying to develop nuclear weapons, of which uranium enrichment is a crucial stage, and says it should be taken to the UN Security Council for possible sanctions.

But Washington does not have support at the IAEA for its hardline stance.

Instead, the board is set this week to consider a British-French-German draft resolution that raps Iran for failing to fully disclose its nuclear activities and calls for it to cooperate further in the agency's investigation.

The so-called Euro-3 are considering amendments to their text from a wide range of IAEA board members, including the United States, which helped in writing the draft, and non-aligned countries which are sympathetic to Iran.

A diplomat close to the talks said the text, based on a report ElBaradei filed ahead of the board meeting, had been modified to take into account ElBaradei's comments and that a second version would be presented soon.

He said that couching the text in ElBaradei's "vocabulary" made it acceptable to most countries.

A US demand to give Iran a deadline for compliance had been rejected since the idea was to give "a sense of urgency at this stage (to resolve the issue) but avoid any idea of deadlines," which could incite a confrontation with Iran, the diplomat said.

The US ambassador to the IAEA, Kenneth Brill, hailed ElBaradei's statement as "a very firm message that Iran can do much better than it has been doing".

ElBaradei said the main enrichment questions the IAEA wanted to resolve were "contamination (by highly enriched uranium particles) we found in some equipment and the question of advanced P-2 centrifuges" which can be used to make bomb-grade uranium.

Highly enriched uranium (HEU) can be used as fuel for a civilian nuclear reactor but also for producing atomic bombs.

The head of the Iranian delegation to the IAEA, Seyed Hossein Mussavian, a member of Iran's Supreme National Security Council, told reporters in Vienna his country has fully cooperated with the IAEA.

He repeated Tehran's assertion that the HEU contamination discovered by IAEA inspectors came from equipment that Iran had brought abroad on the black market and not from Iranian enrichment activities. He said Iran had supplied new information "that would solve the P-2 issue also".

But IAEA officials have said both questions remain open.

Diplomats on the board said they were proceeding carefully since Mussavian had said in Tehran Sunday that Iran was preparing itself for a souring in ties with the IAEA because Tehran refused to renounce its right to enrich uranium for nuclear fuel.

The IAEA board is not expected to debate the resolution until later in the week, possibily Thursday or Friday, diplomats said.

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