Gatlin's drugs ban appeal is rejected, ending his hopes of running in Beijing

Justin Gatlin was ruled out of a defence of his 100metres title in Beijing yesterday just hours after a fresh clampdown on drug cheats by the International Olympic Committee.

The IOC confirmed after their executive met in Athens that those caught for serious drug offences at this year's Games would miss London 2012, however long the sentence imposed by their own sports.

They had intended to bring a new hard line into effect after Beijing but it will apply from July 1.

'Another weaponin the armoury in our fight against doping,' said director of communications Giselle Davies.

The IOC's fear that they would be embarrassed in Beijing by the presence of Gatlin was removed yesterday when the Court of Arbitration for Sport dismissed the American's appeal against a four year drug ban.

It ended his hope of running at next month 's US Olympic trials.

Gatlin was banned for life originally because his positive test in 2006 was his second.

That was reduced by appeals to eight years and finally to four by U.S. arbitration panels because of assistance he gave authorities in their fight against doping.

CAS declined to halve it again when Gatlin argued his first positive test in 2001 was for a prescribed medicine for attention deficit syndrome.

He was the 10th athlete coached by Trevor Graham to be banned for drug-taking.

Graham is awaiting sentence after being found guilty of lying in evidence he gave to federal investigators.

Meanwhile, Dwain Chambers has his final 100m race in Birmingham tomorrow at a British League meeting before launching his High Court appeal against the British Olympic Association's selection ban on all drug-takers.

He is seeking the Games selection standard of 10.21sec.