Busch to Quit Roush Racing

Busch's current team has released a statement saying that the 27 year-old has asked to leave the team early next season, having already signed for another team after his current contract expires at the end of 2006.

The announcement has fuelled speculation that he has been signed to replace the retiring Rusty Wallace at Penske Racing.

A team statement said: "Roush Racing announced today that Kurt Busch has advised team officials that he has signed with another team commencing in 2007. The name of the team is not known. Kurt also requested a release from his contract for 2006. Due to sponsor and team considerations no decision on that request will be made for an indefinite period. Roush Racing will have no further comment at this time."

Busch won 13 Nextel Cup races in 171 starts and won the inaugural Nextel Cup last year, by eight points from Jimmie Johnson at the final race of the season.

The move is likely to kick-start a number of seat changes for next season. Roush Racing is in the middle of a custody battle for Jamie McMurray for 2006, after signing the former 'Rookie of the Year' title holder from 2007. Roush is understood to want McMurray from 2006 when he is still contracted to his current team Chip Ganassi Racing.

If Roush cannot get McMurray released, Mark Martin has said he will delay retirement and stay on for one more year. However, Busch's decision could leave the team still one driver short next season.

One other possible option for Busch is Dale Earnhardt Incorporated. Current driver Michael Waltrip had already announced he would leave the team at the end of the year, and the team had not decided whether it would run a third car in addition to Dale Earnhardt Jr and reigning Busch Champion Martin Truex Jr.