By Karolos Grohmann

BEIJING (Reuters) - Greek sprinter Katerina Thanou has been barred from competing in the Beijing Games because of her involvement in a doping scandal four years ago, the International Olympic Committee (IOC) said on Sunday.

Thanou and fellow Greek sprinter Costas Kenteris were at the heart of the biggest Olympic doping affair in years when they missed a drugs test just before the Athens 2004 Games. The case brought the Olympic movement into disrepute, the IOC said.

Returning from a ban, Thanou qualified for Beijing but needed IOC approval to compete.

"Upon receiving the recommendations of the IOC's disciplinary commission, the executive board has declared Miss Thanou ineligible to participate in the 2008 Beijing Olympic Games," IOC spokeswoman Giselle Davies told reporters.

She said the decision was meant "to send a firm signal of the IOC's moral consideration that this case has brought the Olympic movement very much into disrepute."

Greece's Olympic Committee said it had no choice but to accept the IOC's decision.

"This is an IOC ruling, based on its Olympic charter," Committee President Minos Kyriakou told Reuters. "We just have to accept it and that's it."

He said the Greek team had not been affected by it.

Thanou and Kenteris were banned until December 2006 for violating anti-doping rules after missing the drugs test inside the athletes' village on the eve of the Athens Games.

Thanou, who won the 100m silver medal at the Sydney 2000 Games, has raced only a few times since then but met the Beijing qualifying time and won inclusion in Greece's Olympic team.

"SCANDALOUS SAGA"

The IOC, angered that the doping scandal overshadowed the start of the Athens Games, decided to review the Greek decision. Thanou has warned she would take legal action if the IOC barred her from competing in Beijing.

"There was a whole string of events that took place in this sorry tale. They really resulted in what the IOC sees as a scandalous saga," Davies said.

She said the IOC's decision was unanimous.

The two sprinters claimed to have crashed their motorcycle after missing the Olympic village doping test and then spent four days in hospital. The IOC said they had done so to evade testers.

The athletes, the Greeks' biggest medals hopes on home soil, were then charged with staging the crash and providing authorities with false information.

The start of their trial has been repeatedly postponed and will now take place in early 2009.

Thanou is still to find out whether the IOC will award her a gold medal for the Sydney Games after it was stripped from drugs-tainted U.S. sprinter Marion Jones last year.

The IOC has said it will rule on this after Beijing.

(Additional reporting by Crispian Balmer; editing by Keith Weir)