French police investigating alleged drug abuse in professional cycling detained 15 people for questioning yesterday. They included the nine Festina riders thrown off the Tour last week, three of their team managers and management figures from another Tour team, the Dutch TVM squad.

The Festina riders, who are being held in Lyon, include last year's Tour de France runner-up Richard Virenque, who was aiming for his fifth consecutive King of the Mountains title, the current world road race champion Laurent Brochard, the double Tour of Spain winner Alex Zulle - riding the Tour for the first time this year in the Festina strip - and Tour stage winners Didier Rous of France and the Australian Neil Stephens.

Under French law they can be held for up to 48 hours before being released. Initially it was understood that they would be heard only as witnesses; yesterday Mark Biver, Zulle's manager, maintained that the police had gone back on an undertaking that the riders would not be detained.

Three of the men who run Festina, the directeur sportif Bruno Roussel, the team doctor Eric Ryckaert and the masseur Willy Voet, are currently detained and have been charged with supplying banned drugs; a further three of the team management - Roussel's assistants Michel Gros and Miguel Moreno, and the commercial manager Joel Chabiron - were taken in for questioning yesterday.

Meanwhile, a court in the Belgian city of Ghent said yesterday that local police notes were being sent to France following investigation into medical notes on Ryckaert's computer.

It is a Tour tradition that TVM, winners of the fourth stage of this Tour at Cholet with their sprinter Jeroen Blijlevens, hold a mussels and beer party at their hotel on the rest day. The bash was cancelled on Wednesday, and yesterday morning police called for the team manager Cees Priem, a double Tour stage winner, his team doctor, the Russian Andrei Mikhailov, and a team mechanic.

The mechanic is understood to have been driving TVM's truck when it was stopped by customs men on March 4th on the A26 motorway near Reims and 104 ampoules of the banned blood booster erythropoietin were found on board. The seizure took place four months before customs officers stopped Voet in a Festina team car on the Franco-Belgian border on his way to the Tour de France with large supplies of erythropoietin, steroids and human growth hormone.

The Festina seizure sparked the current inquiry, which led to the organisers of the Tour excluding the team from the race after Roussel admitted combining with the team's doctors and masseurs to supply banned drugs.

Yesterday the Tour organisers had no official statement to make, but were awaiting further developments before deciding what steps to take. If the TVM inquiry takes a similar path to the Festina affair, their exclusion from the race is unlikely to be far away.

Drug scandals notwithstanding, the Tour begins its transition from the Pyrenees to the Alps today. Jan Ullrich takes a lead of one minute 11 seconds over the American Bobby Julich into the mainly downhill 138-mile run from Tarascon-sur-Ariege across the Midi to Le Cap d'Agde on the Mediterranean, though there is likely to be a truce in the race for general classification.