Johnson, Labonte times disallowed

It means that the pair will have to start Thursday's Gatorade Duel races, which decide the line-up for next week's Daytona 500, from the back of the field.

Johnson's time was thrown out because his Lowe's Chevrolet's rear window did not fit the specific NASCAR template, while Labonte's car had an illegal modification to the carburettor.

Both cars had passed the pre-qualifying technical inspection, implying that the window had been changed prior to Johnson's qualifying run.

Johnson, who has fallen foul of NASCAR's strict technical regulations previously, had qualified 5th, and Labonte qualified 28th.

A car with an altered rear window could have improve aerodynamic flow, crucial at a restrictor plate track such as Daytona.

Johnson's car has now been impounded and NASCAR officials have reserved the right to confiscate it for a longer period.

Jim Hunter, NASCAR's vice president for corporate communications, confirmed the decision at a special press conference. He did not rule out further penalties as a result.

"The drivers will be able to compete in the duels on Thursday. But they will have to start from the rear of the field," Hunter said. "If there are any additional penalties as a result of these violations we'll tell you about it, but that is the extent of it tonight.

"Every situation is different and this is the first event of a new season, and we want we start the season with a very thorough inspection. And as far as any prior penalties this will be judged on what happened on today's qualifying procedure. One thing we are concentrating on is making sure our guys stay within the rules."

Hunter suggested that definite actions had caused the cars failure to pass the inspections, the actions taking place between the pre and post-qualifying inspections.

"Johnson's car passed a pre-race template inspection, but when they brought the car back in it was not OK, someone thing had been altered to make it that way," Hunter added. "We wouldn't disallow a qualifying time if it wasn't a serious offence."