Publication of transcripts of police interviews with the Festina riders thrown out of this year's Tour de France after drug allegations have dashed Spanish hopes that this year's Tour of Spain would avoid the doping controversies which dogged the French race in July.

The Vuelta field includes six of the nine Festina riders expelled from the Tour de France and questioned by police in July over the seizure of a team car loaded with erythropoietin (EPO), a banned hormone which increases the quantity of red blood cells.

They include the Swiss rider Alex Zulle, who is going for his third consecutive win in the race, and France's most popular rider, Richard Virenque.

The team's doctor, Erik Rijkaert, remains in prison in Lille, and the manager, Bruno Roussel, is out on bail under the same charge: supplying banned substances for use at sporting events.

In press interviews after the Tour de France, Zulle confessed to using EPO, and so did his team-mate Laurent Dufaux, who has an outside chance of winning the Vuelta. But the transcripts of the police interviews reveal, for the first time, the details of how the hormone is taken, and in what quantities, to build form for major events. A member of the inquiry team has confirmed that the interviews are authentic.

"The biggest doses of EPO were taken closer and closer together just before major races such as the Tour de France," Dufaux told police. "They were taken after some stage finishes in hotel rooms. It was already made up in a syringe brought to me usually by Dr Rijkaert. Afterwards a team helper would collect the syringe and put it in a bin bag."

The presence of Zulle and Dufaux in the Vuelta in spite of such testimonies emphasises the lack of effective action in the six weeks since the Swiss riders first confessed. Admission of drug-taking has the same weight as a positive test, but cycling's governing body, the Union Cycliste Internationale (UCI), has put responsibility for taking action against the riders on to their national federations, who stalled, requesting clear guidelines from the UCI on how to proceed.

Yesterday the Swiss cycling federation said it had called in the two riders for interview on September 30th, three days after the Vuelta finishes and one day before the UCI's deadline for a judgment on the affair.

The French federation, which has to deal with the case of the world champion Laurent Brochard and two of his Festina colleagues, Christophe Moreau and Didier Rous, has said it has been unable to do so because the police have not made the transcripts available.

Virenque has maintained his innocence, claiming ignorance even though, according to his colleagues, EPO was taken widely in the 23-strong team, and in spite of the fact that his winnings from the Tour de France went into a fund used in part to pay for the drugs.

"I obviously cannot be certain that Dr Rijkaert did not administer doping products to me without my knowledge," he told police.

The Vuelta has been rocked by Zulle's assertion in the transcripts that EPO was also widely used at one of Spain's top teams, Once, for whom he used to ride and who include the world number one and Vuelta favourite, Laurent Jalabert.

The team manager, Manolo Saiz, said yesterday: "Anyone who gets a finger stuck up their arse at 5.0 a.m. in a police station will say anything. Zulle was not doped at Once."

The Spanish regard the French police's investigations into drug-taking on the Tour as an unwarranted intrusion and see the publication of the transcripts as the French mounting an attack on their national institution.

"Why September 7th? Why in the middle of the Tour of Spain?" said an editorial yesterday in the sports daily Marca. "Someone in France has it in for Festina and the Vuelta, and because Once have given them a hand they have it in for them, too."

The controversy has spread to the Commonwealth Games, where members of the Australian camp expressed concern over the inclusion of one of the Festina cyclists, Neil Stephens, in their team for the road races this weekend. Stephens, a stage winner in the 1997 Tour, has admitted he may have been given EPO without his knowledge, thinking it was a vitamin injection.

"I question whether the other cyclists will be comfortable racing against him. And I also question the wisdom of the Commonwealth Games allowing him to race," said Australia's International Olympic Committee member Phil Coles.

Don Stockins, the Australian chef de mission at the Games, admitted that there was "a certain amount of discomfort" at Stephens's inclusion. "Certain members of the team felt uncomfortable."

Stephens was defended by Cycling Australia's president, Ray Godkin. "The matter is out of Neil's hands. It is between the Australian federation and the world governing body what happens, and it will be clarified on October 1st."

The Italian Fabrizio Guidi won the 173.5 km fourth stage of the Tour of Spain, from Malaga to Granada, taking over the race lead from Jalabert.