A UFO dropped in on Barack Obama's inauguration ceremony, it was claimed last night. News footage captured a shadowy object flashing across the sky before the new President's speech. The high-speed object appears to streak behind the Washington Monument and then disappear into the clouds.

The CNN clip, featuring veteran US broadcaster Wolf Blitzer, has attracted thousands of hits on video-sharing website YouTube. UFO experts are convinced it shows an alien craft speeding behind the 555ft-high monument - but sceptics say it was a bird or a bat.

Enthusiast Nick Pope said: "We know it is not an aircraft because a strict no-fly zone was imposed over the area. It seems to have been going a little bit too fast for any type of bird."

During the election run-up, UFO bloggers claimed mysterious "orbs" were spotted over an Obama rally in Chicago.

Calls for him to release all information held on UFOs attracted over 170,000 votes on his new online "Citizen Briefing Book" last week - more than any other subject.

Mr Pope said: "Despite the economic downturn and the conflict in Afghanistan, the number one topic people were pressuring the President over was UFOs. It proves this is more than a fringe issue."