Britain's most famous scientist, Stephen Hawking (search), condemned the U.S. led invasion of Iraq as a "war crime" and said Tuesday it was based on lies.

The physicist spoke at an anti-war demonstration in London's Trafalgar Square (search) timed to coincide with the U.S. election. Protesters read out the names of thousands of Iraqis and coalition troops killed since the March 2003 invasion.

"The war was based on two lies," said Hawking. "The first was we were in danger of weapons of mass destruction and the second was that Iraq was somehow to blame for Sept. 11.

"It has been a tragedy for all the families that have lost members. As many as 100,000 people have died, half of them women and children. If that is not a war crime, what is?"

Hawking, the best-selling author of "A Brief History Of Time," was joined by other public figures. Similar events were being held in Spain, Italy, Australia, the United States and Iraq.

"Our message to the U.S. is that the war is illegal and unnecessary, and we want our troops to come home," said Andrew Burgin, a spokesman for demonstration organizer Stop the War Coalition (search). "We also want to highlight the enormous number of Iraqis killed in this conflict who are so often ignored."

In Trafalgar Square, hundreds of spectators holding candles or placards opposing President Bush listened as speakers read the names of the dead while their images were projected onto a large screen.

One group of students from London's Imperial College (search) waved anti-Bush signs, hoping to send a message to U.S. voters.

"If enough people show up tonight at the demonstration, I think a few more voters might notice what we're saying," said Emma Thomson, a student from Scotland who said she was able to cast a vote in Pennsylvania because she was born there.