The CAS upheld the International Association of Athletics Federation's (IAAF) appeal for longer suspensions for middle-distance runners Olga Yegorova, Tatyana Tomashova, Yelena Soboleva, Yulia Fomenko and Svetlana Cherkasova, plus field athletes Gulfiya Khanafeyeva and Darya Pishchalnikova.

The seven athletes allegedly used other people's clean urine to pass doping tests.

The IAAF provisionally suspended the women last July on the eve of the Beijing Olympics following an undercover investigation.

Russia's athletics federation angered the world governing body by applying standard two-year bans backdated to start in spring 2007, when the samples were given.

That would have cleared the women to return at the World Championships, beginning in Berlin next month.

The court's ruling applies bans that run through April 20, 2011.

But the decision means that the athletes are all eligible to compete at the London 2012 Olympics if they qualify.

The IAAF said: "It was unacceptable to the IAAF that these athletes who had committed serious and deliberate breaches of our anti-doping rules would receive an effective ban of approximately 9-10 months."

Yegorova, now 37, won the 2001 World Championship in the 5,000 meters, weeks after she had tested positive for the banned blood-booster EPO.

She escaped a ban and was allowed to run because of mistakes made during the testing process, a decision that led to Britain's Paula Radcliffe staging a protest during the heat that Yegorova competed in in Edmonton.

The 34-year-old Tomashova won 1500m gold medals at the 2003 and 2005 World Championships and finished second to Britain's Kelly Holmes in the Olympics in Athens in 2004.

She is also the current European champion.

The 26-year-old Soboleva won the 1500m world indoor title in 2008, breaking her own world record set the previous month.

Fomenko won the 1,500 at the World Indoor Championships in 2006, and won silver behind Soboleva last year.

The 29-year-old Fomenko finished second at the 2005 World Championships but was disqualified for obstructing another runner.

Cherkasova, now 31, was sixth in the 800 meters at the 2007 World Championships; the 27-year-old Khanafeyeva held the world record in hammer for 12 days in June 2006; and discus thrower Pishchalnikova, 24, is the reigning European champion.