As the Tour de France tries to recapture the hearts of fans and sponsors, another drugs scandal is the last thing it needs. But Iban Mayo has become the third rider to fail a doping test during the tour.

Mayo was found to have taken the blood-boosting substance EPO. The Saunier Duval-Prodir team have suspended the Spaniard pending the results of his B-sample. If it's positive, they will sack their rider, who finished 16th in this year's tour.

Meanwhile T-mobile's Patrik Sinkewitz is refusing to make public the results of his B-sample, after he tested positive for testosterone during training. He was suspended by his team during the tour and many will argue that his silence speaks volumes.

The French government has now stepped in to urge the sport to clean up its act. It's told Tour de France organisers, the Union Cycliste Internationale and the Amaury Sport Organisation, to sort things out. They fell out over this year's scandals but they say they'll patch up their differences. But their conciliatory gesture was tinged with accusations and rancour.

There may be anger but the two sides need to stick together in a swathe of scandal. Kazakh rider Alexander Vinokourov was sacked by his Astana team, after the result of his B-sample confirmed he'd tested positive for a banned blood transfusion after his time trial victory. He now faces a two-year ban from cycling.

All in all that's three riders who failed drugs tests during the tour – including Cofidis rider Cristian Moreni. On top of that, yellow jersey holder Michael Rasmussen was sent home in disgrace – he lied over his whereabouts after missing out-of-competition drugs tests.

It should be the big story in cycling – a triumphant Alberto Contador becoming Spain's first tour winner in twelve years. But with the very future of the sport at stake as fans and sponsors become increasingly disillusioned, it's the cheats and not the champion dominating the headlines.