Vienna, Austria ? Iran said Monday it had frozen all uranium enrichment programs, a claim welcomed by Europe even as it weakened a U.S. push to refer Tehran’s suspect nuclear activities to the U.N. Security Council. President Bush said he hoped the statement was true but “there must be verification.”

Even if verified by the International Atomic Energy Agency — the U.N. nuclear monitor — such a freeze falls short of European and U.S. hopes of an Iranian commitment to scrap enrichment ambitions.

Iran has said suspension will be only temporary and insists that it has the ultimate right to enrich uranium. It dismisses U.S. assertions that it wants to use the technology to make weapons, saying it is interested only in generating nuclear power.

And Tehran’s announcement of a start to suspension came only after it already had converted a few tons of raw uranium into the gas used as feedstock for enrichment. While not prohibited from doing so until Monday — when the freeze took effect — conversion continued until shortly before the deadline, raising doubts about Iran’s interest in dispelling international concerns.

“Iran suspended uranium enrichment (and related activities) as of today,” Iranian state radio said Monday. In Vienna, home to the IAEA, agency head Mohamed ElBaradei said: “I think pretty much everything has come to a halt.”

Bush said Iran must “earn the trust of those of us who are worried about them developing a nuclear weapon.”

“Let’s say I hope it’s true,” Bush said at a news conference in Cartegena, Colombia. But, he added, “I think the definition of truth is the willingness of the Iranian regime to allow for verification.”

ElBaradei said he expected to have a definitive ruling by Thursday on whether Iran had honored its pledge to stop all activities covered by the freeze, among them producing the uranium hexafluoride gas that can be enriched either to low-grade nuclear fuel or high-level weapons grade uranium used for the core of warheads.

Britain — a key negotiator of the Nov. 7 deal that promises Iran technical and political support from the European Union in exchange for the suspension — cautiously welcomed the move while making clear it would watch closely for its implementation.

“Clearly the important thing is that on the one hand Iran is showing signs of compliance,” said the office of Prime Minister Tony Blair. “But equally the important thing is that it does so.”

Still, the suspension — if verified by IAEA inspectors — will take the wind out of a U.S. push to have Iran referred to the Security Council, a goal the Americans have pursued since the start more than a year ago of an agency probe into suspect Iranian dual-use nuclear activities.

The suspension was clearly timed to Thursday’s start of a 35-nation IAEA board meeting and met a key demand of the last board meeting in September. It thus deprived the Americans of arguing that Tehran was defying the U.N. agency.

British Foreign Secretary Jack Straw warned that if Iran reneged on the deal, the European Union “reserves the right” to seek U.N. sanctions against the country.

While not prohibited from enrichment under the Nuclear Nonproliferation Treaty, Iran has been under intense pressure to agree to at least a freeze — if not to scrap its program — as a way of reducing international suspicions.