By Mark Heinrich
VIENNA (Reuters) - The U.N. nuclear watchdog said on FridayIran had failed to explain Western intelligence reports showingexplosives and missile work linked to the production of atomicbombs and that this was a "serious concern".
But the International Atomic Energy Agency (IAEA) also saidIran had increased cooperation with U.N. inspectors in the pastfew months.
The United States, which has accused Iran of having asecret programme to build nuclear weapons, said Tehran hadfailed to meet U.N. demands and that it would go on pressingfor new sanctions against the Islamic Republic.
Senior diplomats from Britain, France, Germany, the UnitedStates, China and Russia would meet in Washington on Monday todiscuss the next steps over Iran's nuclear programme, Westernofficials said.
The IAEA findings, which also said Iran had failed to clearup all outstanding questions by an agreed February deadline,may be branded negative on balance by big powers and spur theU.N. Security Council to adopt more sanctions as early as nextweek.
Iran, which says its nuclear programme is only for powergeneration to meet the growing demands of its economy, hailedthe IAEA's comments as a victory because it said the watchdoghad found Tehran was pursuing peaceful activities.
The IAEA said in a report Iran was being more open withU.N. monitors than before but that Tehran was testingtechnology that could give it the means to enrich uranium muchfaster.
In unusually strong wording, the IAEA said Iran had not sofar explained documentation pointing to undeclared efforts to"weaponise" nuclear materials by linking uranium processingwith explosives and designing of a missile warhead.
"In the last four months, in particular, we have made quitegood progress in clarifying the outstanding issues," IAEADirector Mohamed ElBaradei said in a statement accompanying thereport, assembled by senior IAEA inspectors.
"On that score, Iran in the last few months has provided uswith visits to many places that enable us to have a clearerpicture of Iran´s current programme," said ElBaradei.
"However, that is not in my view sufficient," he said.
CRUCIAL REQUIREMENT
ElBaradei said one crucial requirement was for Iran toimplement the IAEA's Additional Protocol, which allows snapinspections that could verify that Tehran is not engaged insecret bomb work beyond declared civilian atomic energy sites.
Another issue was Iran's failure so far to address Westernintelligence, published for the first time by the report, aboutcoordination between uranium processing, missile warhead designwork and high-explosives tests, he said.
"The issue is still critical for us to be able to come to adetermination as to the nature of Iran´s nuclear programme."
ElBaradei said Iran should heed U.N. Security Councildemands for a suspension of all uranium enrichment activity asa major step towards easing mistrust.
But he expressed satisfaction U.N. inspectors had been ableto clarify all outstanding past issues about the programme,except for weapon making, in the past few months because Iranhad provided credible answers that had been withheld earlier.
"We are disappointed with Iran's continued failure tocomply with its U.N. Security Council obligations and calls bythe IAEA to suspend all proliferation-sensitive nuclearactivities," said senior U.S. official Kate Starr.
"While we welcome the progress the IAEA has made on someissues, until Iran meets its obligations the internationalcommunity can have no confidence that Iran's nuclear programmeis peaceful," said Starr, a spokeswoman for the White HouseNational Security Council.
In Tehran, Iran's chief nuclear negotiator Saeed Jalilitold a news conference: "(The IAEA report) is another documentwhich proves the Iranian nation was right about the nature ofits nuclear activities.
"This report showed that our activities are peaceful."
(Writing by Ralph Gowling, editing by Stephen Weeks)
