"The samples did not show any adverse findings," said International Olympic Committee (IOC) spokeswoman Giselle Davies at a hastily convened news conference on Friday.

But Arne Ljungqvist, head of the IOC's medical commission, said the first tests were made on urine samples. Fresh tests are to be carried out on blood samples which will be taken only when the athletes have finished in the Games.

Those, he said, will reveal if any of the 10 athletes attempted blood doping just before competing.

Ljungqvist said signs of blood tampering will remain in the system for up to three weeks after being carried out.

The urine tests were carried out last Saturday after a police raid on the Austrian biathlon and cross-country squads' base in the Italian Alps.

Italian police had been tipped off that Walter Mayer, the squad's coach but banned by the IOC because of links to blood doping at the Salt Lake City Games in 2002, was with the athletes.

Documents and other items linked to the inquiry were seized and Italian police opened an immediate investigation.

A second raid was carried out on Monday night at separate premises.

Despite the first negative results the IOC have no intention of letting the matter drop and will set up a disciplinary commission later this year to investigate the 'Mayer affair'.

"It has started and it will go on," said Ljungqvist. "This is ongoing."

Davies also warned that the investigation is far from over.

"The IOC would like to stress that the doping controls on Saturday and their results are only one part of this wide affair," added Davies.

"We must look at the bigger picture."

Italian prosecutor's say they already have enough evidence after last weekend's raid for the International Olympic Committee (IOC) to take sanctions against them.

Prosecutor Ciro Santoriello said there was no doubt the IOC will be able to act.

"Part of the testimony we already have confirms that the IOC can take sanctions against the athletes. But as the investigation is still ongoing we have not yet been able to hand over the evidence to the IOC," Santoriello told French sports daily L'Equipe.

Ljungqvist said the IOC was awaiting the police report on what products were found in the athletes' apartments and in the nearby area.

He added that if any of the substances taken by police were on the banned list that would be enough to convict an athlete.

But he stressed that this was not an IOC attack against the Austrian team.

"We don't want to give the image that this is a witch-hunt. This is not the case," he said. "But we have good reason to check."

Following the swoops, Mayer was sacked as coach of the biathlon and cross-country teams, arrested in Austria and then charged with a number of offences including drink-driving after he tried to smash through a police road block.

He has since been admitted to a psychiatric hospital.

Of the ten Austrians tested in the first raid on Saturday, two of them - Wolfgang Perner and Wolfgang Rottman - have since left Italy and been kicked off the team.

Only one positive dope test has been returned to date - that of Russian biathlete Olga Pyleva who was stripped of a silver medal and expelled from the games after testing positive for banned substance carphedon.

(AFP)