In the latest sign of a growing intolerance to dissent against the war, imagined or real, protesters in Louisiana used a tractor to crush compact discs and other items from the band as the boycott on the airwaves intensified.

In recent weeks a man has been arrested for wearing an anti-war T-shirt in a shopping mall in Albany, New York; a county councillor who passed an anti-war resolution was encouraged to leave town in Pennsylvania; and one of President Bush's senior advisers branded a journalist who wrote a critical article about him as "the closest thing journalism has to a terrorist".

The furore over the Dixie Chicks, who performed at this year's Super Bowl, started after one of the singers, Natalie Maines, told a London concert last week: "Just so you know. We're ashamed the president of the United States is from Texas."

Once her comments were reported in America the fallout was almost instant. One media group, Cumulus Media, instructed all its 42 country stations to stop playing the group's music until further notice, according to one music news sheet.

In Houston, country station KKBQ-FM had been airing the chart-topping song, Travelin' Soldier, an average of 12 times a day, according to USA Today. On Friday, after a poll on its website ran nearly 3-1 against playing the trio's music, programme director Michael Cruise called a halt.

Sales dropped by 15%, pushing it down to third place in the billboard charts. "Airplay for the Chicks did start to erode on Friday," says Wade Jessen, Billboard's country chart editor.

Not even an apology from Maines could stem the decline. "My remark was disrespectful. I feel that whoever holds that office should be treated with the utmost respect," she said. "While war may remain a viable option, as a mother, I just want to see every possible alternative exhausted before children's and American soldiers' lives are lost."

So far efforts to silence both critics and criticism of the war and its leading proponents have been isolated and sporadic. In the small Pennsylvania township of Haines, officials who passed an anti-war resolution were forced to rescind it and told to leave town after an angry meeting.

The row ignited after a Swiss television crew came to report on the town, leaving some locals feeling that their representatives were being unpatriotic. "We were being used as propaganda overseas against our president," Ray Decker, chairman of the supervisors, told the New York Times.

Locals called another meeting at which the resolution was revoked. "It was a very angry meeting," says Daniel Brannen, who proposed the resolution. "There were a certain amount of personal attacks and some of us were labelled outsiders and asked to leave the area." Mr Brannen grew up in a town 20 minutes away.

The media have also come under fire from conservatives for simply raising questions. After the New Yorker's Pulitzer prize-winning writer Seymour Hersh wrote an article questioning the former assistant defence secretary and Bush adviser Richard Perle's business dealings with Saudi na tionals, Mr Perle threatened to sue him through the London courts and branded him "the closest thing American journalism has to a terrorist."

This month Stephen Downs was arrested for trespassing in a mall near Albany after refusing to take off his T-shirt which said "Give peace a chance" on the back. The mall decided not to pursue the case.