Mohamed ElBaradei also said that Iran had not given access requested by the IAEA to the Lavizan and Parchin military sites, where diplomats say weaponization work is suspected.

Diplomats told AFP the agency had also requested but been denied access so far to interview key officials such as Mohsen Fakhrizadeh, a brigadier general who has worked at Lavizan.

Information is lacking over how close Iran is to being able to use sophisticated centrifuges for enriching uranium as well as its links to international nuclear smuggling, ElBaradei told a meeting of the 35-nation board of governors of his International Atomic Energy Agency (IAEA).

Speaking after being elected Monday to a third four-year term as IAEA director general, ElBaradei, 62, said the IAEA investigation of Iran would continue, even if progress was being made on some fronts.

"Iran has provided some additional documentation and information, which are not yet sufficient to answer several remaining questions," ElBaradei said.

His comments came as Iran was seeking to have a more than two-year investigation of its nuclear program closed, especially since it is negotiating with the European Union to guarantee it is not secretly developing atomic weapons and to win trade, security and technology benefits.

Iran says its nuclear program is peaceful and designed to generate electricity but the United States says this civilian effort hides a covert atomic weapons program.

ElBaradei, who was elected after the United States dropped its opposition to his candidacy, also formally declared Tuesday his support of a US proposal "to establish a committee to consider ways and means to strengthen the safeguards system."

ElBaradei said the IAEA had set up a similar committee in 1996 to fix weaknesses in monitoring Iraq's nuclear program.

Now "revelations such as the discovery of additional undeclared nuclear programs aided by covert nuclear supply networks and the risk associated with nuclear terrorism have confronted the agency's verification system and the non-proliferation regime in general with unprecedented challenges," he said.

ElBaradei's deputy director general for safeguards Pierre Goldschmidt is later in the week to provide a detailed briefing to the board on the current state of the Iran investigation.

ElBaradei said the IAEA "is making progress on one of the two key remaining issues, namely the origin of the low and high enriched uranium contamination on equipment at various locations in Iran."

The agency is working to establish whether highly enriched uraniumits inspectors have found in Iran is from imported equipment, as Tehran claims, or from Iranian manufacture of such potentially weapons-grade nuclear material.

A diplomat close to the IAEA said the tests on centrifuge parts supplied by Pakistan tend so far to support Iran's claim that the contamination was from imported equipment.

But the diplomat said the tests had not been concluded.

The other main remaining issue is the IAEA's investigation of Iran's acquisition of P-2 centrifuges, which are speedier than earlier models in enriching uranium that can be used to make fuel for civilian nuclear reactors but can also make up the explosive core of atom bombs.

The issue involves the nuclear technology and materials black market run by disgraced Pakistani scientist Abdul Qadeer Kham, and which supplied Iran, as well as Libya and North Korea.

ElBaredei said the IAEA continued to press Tehran for "additional documentation regarding offers of equipment made to Iran, as well as for information on associated technical discussions between Iran and intermediaries in the procurement network," a reference to the international black market in smuggling nuclear materials and information.

ElBaradei said the IAEA had asked Iran "to reach agreement on modalities, currently under discussion, that would provide the agency with access to dual-use equipment and other information related to the Lavizan-Shia site and would allow additional agency visits to areas of interest at the Parchin site."

Dual-use equipment can be used either for peaceful or military purposes.

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