NASCAR placed drivers Kurt Busch and Tony Stewart on probation for six races Tuesday, beginning with the Daytona 500.

The punishment stems from a confrontation between the two former series champions, who wrecked in practice last week and then carried it into the NASCAR officials' trailer.

NASCAR spokesman Ramsey Poston said the drivers were disciplined solely for the on-track portion of their clash, when the drivers deliberately used their cars as battering rams.

"We will continue to keep a check on this sport and won't let it get out of hand," Poston said. "If there is a repeat between these two, then we will take it much more seriously."

Although Busch and Stewart confronted each other during a closed-door meeting with NASCAR officials after the incident — and it was widely believed that Stewart punched Busch, speculation that no one would either confirm or deny — Poston stressed that nothing that happened off the track factored into their discipline.

And while it was Busch who slammed his car into Stewart's as they exited the track, Poston said both drivers were punished because they were involved.

NASCAR officials came into this season saying drivers would be given more latitude to show emotion this year, and the relatively light nature of Tuesday's punishments would seem to support that.

Poston said the measures would have been more severe if Stewart and Busch had rubbed fenders while pit crew members were working on pit road, endangering their safety.

"We took a lot into consideration," Poston said. "The drivers do have greater latitude, pit road was closed, there was no personnel on the track. It's an emotional sport, there's emotion on the track. They should not have been banging each other after the accident. But they were not banging each other on a 'hot' pit road. That is very different and would have been dealt with much more severely."

But even as they take a more permissive attitude toward driver misbehavior, Poston said NASCAR officials are going to begin making probation more meaningful.

In the past, officials haven't necessarily punished a driver more harshly if he misbehaves while on probation. Poston said that's going to change.

"In the past we've used 'probation for the rest of the year,' but it's never been something that's been exercised. It never seemed to really mean anything," Poston said. "Now we are going to take action. If you are on probation for an altercation with another driver, and you have a second incident during that probation period, we are going to take action."