WASHINGTON -- U.S. intelligence officials will show members of Congress a videotape laying out the evidence that Syria was building a nuclear reactor with North Korean assistance before it was bombed by Israeli planes in September 2007, a U.S. official said Wednesday.

Intelligence officials who have seen the evidence consider it "extremely compelling,'' the U.S. official said. He spoke on condition of anonymity because of the sensitive nature of the information.

The Syrian reactor was similar in design to a North Korean reactor that has in the past produced small amounts of plutonium. It was not yet complete but was far enough along to demonstrate a resemblance to the North Korean reactor at Yonbyon.

The U.S. official said no uranium -- the fuel for a reactor -- was evident on site. Syria has maintained in the past that the site was an unused military facility.

Syria did not declare the apparent reactor to the International Atomic Energy Agency nor was it under international safeguards, possibly putting Syria in breech of an international nuclear nonproliferation treaty.

Plutonium-producing reactors are of international interest because plutonium can be used to make high-yield nuclear weapons or radiological or "dirty'' bombs.

Israeli warplanes bombed a site in Syria on Sept. 6, 2007, that private analysts say appears to have been the site of a reactor, based on commercial satellite imagery taken after the raid. The site later was razed.

U.S. officials said Israel shared intelligence with the United States before the bombing after administration officials expressed doubts that the site was a nuclear reactor built with North Korea's assistance, according to The Washington Post, which first reported the existence of he videotape on its website Wednesday.

The Senate and House intelligence committees were scheduled to be briefed about the North Korea-Syria connection on Thursday, and several other panels such as the Senate Armed Services Committee were expected to be briefed as well.