The founder of an American ice-cream chain known for its liberal politics is sending a huge effigy of George W. Bush on a trailer around the United States, showing the U.S. president with his pants on fire.

Ben Cohen, who co-founded Ben & Jerry's Ice Cream, told a Seattle newspaper that he's exercising his right to freedom of speech to expose what he sees as Bush's untruths during a presidential election year.

"In a polite society, you don't go up to a person and look at them in the face and say, 'You're a liar.' We think it's a lot more dignified and there's a lot more decorum to say, 'Excuse me sir, your pants are getting a little warm, don't you think?'"

Ben Cohen demonstrates the set up on an effigy of President Bush. (AP photo)

Cohen calls his stunt the "Pants on Fire Tour," playing off the childhood taunt "Liar, liar, pants on fire."

Volunteer drivers are trained to pull the trailer holding the 3.7-metre effigy of Bush, which includes fake flames and smoke shooting out of the character's pants and a screen on the front which scrolls through a number of Bush's disputed statements.

The effigy is wearing a flight suit with the words "Mission Accomplished" on the back, referring to his declaration on May 1, 2003, that major hostilities had ended in the Iraq occupation. Since that time, more than 700 American military personnel have died in Iraq.

A White House spokesman would not comment on the effigy, other than to say that Bush supports free speech and believes most Americans support his policies.