Bruno Roussel, director of the Festina team, and Eric Ryckaert, the team's doctor, have been moved to the northern city of Lille as police continue to investigate allegations of doping.

Eric Ryckaert: Protesting innocence

Mr Roussel has been suspended by the sport's governing body pending an inquiry, though the team are still racing.

Police took the men in for questioning after they had arrested a team masseur, Willy Voet, who was caught carrying 400 bottles of a performance-enhancing drug used by cyclists.

He is also being held in Lille and it is expected that investigating judge Patrick Keil, responsible for questioning Mr Voet, will interview the other men.

But there are growing fears that the doping scandal, potentially the biggest to hit a sport already beset by allegations of drug use, could irreparably damage one of France's most prestigious events.

'Festina suspicions'

Heink Verbruggen, President of the International Cycling Union (UCI) said that there had been suspicions about the Festina team before the arrest of masseur Willy Voet.

He said: "We already had our doubts about the team over the case of Christophe Moreau's positive test in June for anabolic steroids which Roussel told me personally was the fault of a masseur.

"However, our enquiries suggested it is more the environment that the masseur works in than the person himself which must be questioned.

"It's a bitter blow for cycling. We realise that there are many riders who take drugs which cannot be detected."

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Festina, one of the world's most successful teams, includes Laurent Brochard, the world road race champion, four times King of the Mountains Richard Virenque and Alex Zulle, much favoured to challenge for this year's Tour title.

One French newspaper, Le Parisien, has reported that Mr Roussel and Mr Ryckaert were named in a Belgian investigation into the supply of EPO, a drug which improves the transport of oxygen in the blood stream.

Following Mr Voet's arrest, police raided the Festina team's Lyon headquarters where they say they found anabolic steroids and chemical masking agents.

Mr Roussel said he was "stunned" by the scandal but has denied any wrongdoing.

Speaking to the French newspaper, L'Equipe, Mr Ryckaert said he had been "broken" by the allegations.

Strongly denying any involvement in doping riders, he said: "My wife knows me, and she knows that everything they are saying about me is a serious lie".

Team 'traumatised'

The French prime minister, Lionel Jospin, watched the developments with sadness - but not total surprise.

Lionel Jospin: Demanded answers

He insisted "that light be shed, and conclusions drawn".

Richard Virenque said the team had been traumatised by the arrests.

"This is a nightmare we are living through," he said.

"We came into the Tour with real prospects of taking the Tour whether it was me or Alex Zulle.