In the most heated and controversial part of Sunday's Academy Awards, filmmaker Michael Moore harshly criticized President Bush for the war in Iraq.

"We live in the time where we have fictitious election results that elect a fictitious president," Moore said while accepting the Oscar for his anti-gun documentary Bowling for Columbine. "We live in a time where we have a man who's sending us to war for fictitious reasons."

Moore brought the other documentary nominees on stage with him in what he called a show of solidarity for nonfiction during these "fictitious times."

"We are against this war, Mr. Bush. Shame on you, Mr. Bush. Shame on you," Moore shouted from the stage.

Some in the audience loudly booed while others applauded and others still remained silently in their seats.

Afterward, host Steve Martin tried to restore levity to the ceremony.

"It was so sweet backstage, you should have seen it," Martin joked. "The Teamsters were helping Michael Moore into the trunk of his limo."

Bowling for Columbine refers to the fact that gunmen Eric Harris and Dylan Klebold went bowling before they opened fire at Columbine High School in Colorado, killing 12 students and a teacher before turning the guns on themselves.

Asked backstage why he made the remarks, Moore answered: "I'm an American."

"Is that all?" a reporter asked.

"Oh, that's a lot," Moore responded.

The scruffy-bearded activist from Flint, Mich., also directed the 1989 documentary Roger & Me, in which he pursued former General Motors Corp. boss Roger Smith to confront him about the collapse of the auto industry in Moore's hometown.

He's also the author of the best-selling book Stupid White Men ... And Other Sorry Excuses for the State of the Nation, which criticizes American politicians for favoring corporate wealth over public well-being.

The Associated Press contributed to this report.