Morgan Gardner, 12, destroys her Dixie Chicks CD in protest

Airplay for the group's songs is down 29% on country stations, and 20% on general music stations around the country, a monitoring group has said.

The Texas female trio's CDs have been burned and smashed - and even run over by a tractor in one event organised by a Louisiana country station.

It follows a remark by singer Natalie Maines in London that the group was "ashamed" that Mr Bush was from Texas.

Radio stations reported receiving a flood of protests from listeners angered by the comment.

Radio monitoring service Mediabase 24/7 said that airplay for the group had dropped on all US radio stations by about a fifth in a seven-day period.

Mediabase president Rich Meyer said: "Radio generally reflects the mood of the country.

Singer Natalie Maines, centre, has apologised for the remark

"If radio perceives that its listeners are upset with the Dixie Chicks, they will respond accordingly."

Mr Meyer said the group may have repaired some of the damage after Maines issued a public apology for her remark.

In a statement she said: "As a concerned American citizen, I apologise to President Bush because my remark was disrespectful.

"I feel that whoever holds that office should be treated with the utmost respect.

"I just want to see every possible alternative exhausted before children and American soldiers' lives are lost. I love my country. I am a proud American."

Despite the furore, the Grammy-winning group's album Home did not budge from the top spot in the country charts.

Their single Travelin' Soldier fell briefly from the number one spot, but climbed back to the top again.