Athletes including Dougie Walker, Linford Christie and Gary Cadogan have been suspended from competition after the sport's ruling body toughened its stance towards doping.

At a meeting in Monaco on Saturday, the IAAF announced that all athletes who had tested positive for banned substances - including Nandrolone - would be suspended, pending their appeals being heard by the body's arbitration panel.

Until now, athletes who have been cleared of taking illegal substances by their national federations, but whose cases have been referred to the IAAF, were eligible to continue in competition.

The other athletes affected by the new laws include Jamaican sprinter Merlene Ottey, Israel's Itai Margalit, Brazil's Andre Luiz Ramos and Javier Sotomayor of Cuba.

In a statement, the IAAF said: "As of midnight on 13 February, any athlete who has been cleared by his or her national federation of a doping offence, but whose case has been sent to arbitration by the IAAF, will now be suspended from competition until the conclusion of that arbitration."

Christie, the former Olympic sprint king, tested positive for the steroid Nandrolone after an indoor meet in Germany last February.

Cadogan and Walker both tested positive for the drug last year.

All three have been cleared by UK Athletics.

Walker 'shattered'

Walker's coach, Dave Gibson, said the 200-metre Scottish sprinter, would be "shattered" by the IAAF's decision.

"I heard on television it was possible that Doug and other British athletes might undergo tests," he said.

"I think he will be shattered, but as you know his lawyer [Nick Bitel] has already issued a writ against the IAAF saying they have not got the authority to impose a suspension.

"I think the news is drastic. But it is within their [IAAF's] powers and really they are defending their own position.

"You cannot open the floodgates and give amnesties to everyone. You must judge each case on its own merits."

Positive test kept secret

The IAAF also revealed British pole vaulter Mike Edwards tested positive for a cocktail of drugs including the anabolic steroid stanozolol last year.

Stanozolol was the drug found in the urine samples of Ben Johnson when he tested positive after winning the 1988 Seoul Olympic 100m final.

Edwards tested positive on 3 March last year and was subsequently cleared by UK Athletics on 21 December. The case was not made public.

IAAF vice-president and medical committee chairman Arne Ljungqvist said the Edwards' case would be referred to the IAAF's doping commission. The doping commission can recommend the case be referred to arbitration.

Mr Ljungqvist said UK Athletics' decision to keep the Edwards' case secret contravened IAAF rules.

"This is the British system and the US system too," he said. "It is against our rules. Our rules say that you have to announce the result after the A [first] sample is announced."