Washington:  When US officials on Thursday rolled out evidence to support allegations that North Korea had helped Syria construct a nuclear reactor, they said the intelligence community had "low" confidence that the purpose of the reactor was to produce plutonium for nuclear weapons.

Some experts are questioning the strength of the intelligence included in the high-profile presentations that were made to more than 200 members of Congress on Saturday and later to the media.

"The end result has been far more speculation about the meaning and credibility of US reporting than should have been the case," said Anthony Cordesman at the Centre for Strategic and International Studies.

"Once again, the US intelligence community has created an unnecessary mess by rushing out a half-complete product, and failing to put the information in releases in proper context." Meanwhile, a nuclear physicist close to the International Atomic Energy Agency (IAEA) cast doubt yesterday on the veracity of US intelligence.

"When you look at the [US intelligence services] pictures, they show only raw construction," an expert close to the IAEA said.

"It was just the shell of a site, and the walls did not look like the ones needed for a plutonium reactor."

Walls of a plutonium reactor "need a lot of piping, there was nothing like that on the pictures", he added.