French police have launched an investigation into the attempted sabotage of the Tour De France on Sunday.

Thirty riders, including defending champion Cadel Evans, suffered punctures on Stage 14 of the race after a cluster of tacks were scattered across the track around 200 metres from the summit. The unidentified culprits remain at large.

Brit Bradley Wiggins was praised for his "fair play" after he slowed the competitive race to allow the affected riders to catch up with the peloton, which eventually crossed the finish line as one.

"It was obviously done on purpose. We have the tacks but we don't know who spread them. They are imbeciles," said race official Jean-Francois Pescheux.

Three years ago, two Tour de France riders, Spain's Oscar Freire and New Zealand's Julian Dean, sustained minor injuries after being shot at in an air rifle attack.