Michelin has promised to fully investigate the cause of the high-profile punctures that were to eliminate Jenson Button and Juan Pablo Montoya from the Belgian GP, and caused David Coulthard to lose out on a higher points finish.

"We are obviously looking into the three incidents," confirmed Pierre Dupasquier, the French manufacturer's motorsport director. "In each case, the right rear was affected - and that suffers the least severe loads around a lap of Spa.

"What's more, the incidents all occurred at different stages in the tyres' life cycles," he revealed. "In Coulthard's case, there is a clear cut on the inside wall of the carcass.

"In the past, we have seen similar instances where a tyre has been damaged by passing over a kerb's sharp inside edge," he added. "It is too early to know for sure if that happened on this occasion, but it is bizarre to have three apparently similar problems and our analysts are already investigating the cause. We will find out the root cause."

On Friday, Toyota tester Ryan Briscoe crashed heavily at Eau Rouge following a left-rear blow-out. This was subsequently blamed on the new kerbs at the re-profiled Bus Stop chicane.