Lance Armstrong was still wearing the yellow jersey last night, but the fears of the Tour de France organisers were realised with the American denying media insinuations that his performances could be the result of drug use.

Although Armstrong cancelled a press conference yesterday and there were also indications that his US Postal Services team backup staff had been warned against speaking to the press, he dismissed the allegations emphatically.

"It's not true. It's incredible they can print that," he said. "I have been concentrating on this race for the entire season. I did two training camps and spent two weeks in the Alps and another in the Pyrenees. I checked out all the mountain stages."

Yesterday's victory by the former spray-painter Ludo Dierckxsens was overshadowed by the French media reports sniping at Armstrong's success. L'Equipe said: "Armstrong is so much stronger that the Tour caravan has abandoned itself to unease." Le Monde went through the Texan's performances in the mountain stages in the only Tour he has finished to date, the 1995 race. He finished between 18 and 32 minutes behind the winner on each of the Alpine and Pyrenean legs.

There have also been exchanges between Armstrong and Christophe Bassons, the French rider who, in a column in the Aujourdhui newspaper on Wednesday, said that the American's victory at the Italian ski resort of Sestriere the previous day "had disgusted many riders".

Bassons had been verbally abused by his fellow riders already in this Tour over his willingness to talk about the fact that he does not use drugs. The word is that he will not now be receiving any contracts to ride the criteriums, the local races next month in which Tour riders are paid individually by agents to turn up; if so, that is strange behaviour in a sport which is keen to rehabilitate itself after last year's scandals.

Armstrong's team have put his improvement down to hard work and the fact that he lost 11 kilos during his cancer treatment. "I don't think anyone can believe it," said his manager Mark Gorski. "It's like a miracle." He added that "because of the events of the last 12 months, this is the cleanest Tour de France in many years and the best athletes are rising to the top". There is no evidence to suggest otherwise.

Yesterday belonged to a breakaway group of seven second-stringers who are no threat to the overall standings. Dierckxsens, the 35-year-old Belgian champion who crossed the line 12 miles ahead of the peloton, was at a dead end six years ago, working in the paint shop at the Daf car factory near Antwerp. This is not a happy Tour but there is still room for some romance.

Meanwhile, Italian rider Marco Pantani said yesterday he will race at the World Championships in October, scotching fears he would retire after being kicked off the Tour of Italy for failing a blood test.

The 1998 Tour de France winner said that popular support and his love of cycling had swayed him away from retirement, and added that he had put the events surrounding his test failure behind him.

Pantani paid tribute to Lance Armstrong, the Tour de France leader. "If you had to choose the important man in this Tour, I think it would have to be Armstrong," said the Italian.

"He's someone who has had very serious problems and he deserves a great deal of credit for the fact that he's out there now fighting, and winning this Tour hands down.

"Once again, the Tour de France has found a worthy winner."

Pantani had been leading the Giro d'Italia but was banned from starting the penultimate stage at Madonna di Campiglio on June 5th after a test showed his red corpsucle count to be 52 per cent, above the safety limit of 50.

A high count suggests the use of Erythropoietin, or EPO, which boosts the number of red blood cells which carry oxygen around the body, and markedly improves endurance. However, a test failure is not proof of EPO consumption.

Pantani, who also won the Tour of Italy last year, has strongly denied ever having used performance enhancing drugs, and was embittered by the tests results - which he has contested.

The Italian highlighted the amount of popular support he has received in recent weeks.