April 25 (Bloomberg) -- The United Nations nuclear agency said it will investigate ``with seriousness'' allegations that Syria built a atomic reactor and criticized the U.S. for failing to hand over the incriminating data earlier.

Mohamed ElBaradei, the director general of the Vienna-based International Atomic Energy Agency, said the U.S. had provided information yesterday showing that a Syrian installation destroyed by Israel last September was an undeclared reactor. The IAEA chief also criticized Israel's ``unilateral use of force'' for hampering the agency's ability to verify Syria's activity.

``The agency will treat this information with the seriousness it deserves and will investigate the veracity of the information,'' ElBaradei said in a statement today. He said the data showed the alleged reactor wasn't yet operational and that no nuclear fuel had been fed into it.

The White House says the reactor, in a remote location in Syria's western desert, was built with North Korean assistance and outfitted to produce plutonium, an ingredient for a possible nuclear weapon. President George W. Bush's spokeswoman, Dana Perino, said yesterday the U.S. had ``good reason'' to believe the reactor ``wasn't for peaceful purposes.''

Syria, which must conform to IAEA safeguards as a signatory to the nuclear Non-Proliferation Treaty, failed to inform the atomic agency of the reactor and destroyed evidence after the installation was bombed, Perino said in yesterday's statement. The U.S. also released a computer-animation presentation that showed pipelines running from the Euphrates River to an underground cooling pool next to the Syrian installation.

Ordinary Military Building

Syria's ambassador to the U.S., Imad Moustapha, yesterday called the facility an ordinary military building and described the allegations as ``silly.'' Speaking to CNN, Moustapha said the Bush administration ``has a proven record of fabricating'' evidence on other countries' weapons of mass destruction, referring to faulty evidence of Iraq's weapons programs.

U.S. intelligence officials until yesterday had been silent on the possible North Korea connection to the bombed installation. Israeli officials have refused to discuss the issue since Syria last year said Israeli warplanes had carried out a raid on its territory.

``The director general views the unilateral use of force by Israel as undermining the due process of verification that is at the heart of the non-proliferation regime,'' ElBaradei said.

To contact the reporter on this story: Patrick Donahue in Berlin at at pdonahue1@bloomberg.net.

Last Updated: April 25, 2008 06:53 EDT