MARK Richardson, currently Britain's No.1 400 metres runner, yesterday said he would quit athletics if he fails to clear himself of doping allegations.

He is the latest world-class competitor to be linked to use of nandrolone, the substance which has sparked a worldwide explosion of positive drug readings in the past two years.

Edinburgh's European 200m champion Dougie Walker, Olympic and world 100m champion Linford Christie, and UK international 400m hurdler Gary Cadogan are among 17 Britons to be named.

Elsewhere, victims include Germany's 1992 Olympic 5000m champion Dieter Baumann, Jamaican world sprint champion Merlene Ottey, French World Cup striker Christophe Dugarry, Australian Open tennis champion Petr Korda, French Olympic judo champion Djamel Bouras, leading Swiss triathlete Olivier Bernhard, and Canadian roller-hockey goalkeeper Steve Vezina.

Willing to take a lie detector in a bid to clear his name, the 27-year-old Richardson insists he is innocent, but now faces a lengthy and costly campaign to salvage his athletics future.

Runner-up for the Commonwealth title in 1998, and older of world gold and Olympic silver medals in the 4 x 400m, he was, until yesterday, central to a British dream of Olympic relay gold in Sydney.

Now, he is one more athletics pawn to be manipulated through court-rooms and official hearings, facing a two-year ban.

It is 13 months since Walker succumbed to the epidemic. He was subsequently cleared by UK Athletics, whose experts believe that the substance, which occurs naturally, can also come from legal sources, rather than proscribed anabolic steroids. That verdict was rejected by the world organisation, the International Amateur Athletic Federation, whose view, reiterated yesterday, is that an athlete is responsible for whatever appears in his urine.

Walker has not raced since December, 1998, and is taking legal action against both bodies.

He is currently awaiting an arbitration hearing originally scheduled for April. ''But that might be well into the summer now, because of litigation,'' he said.

''I'm desperately sorry for Mark. I don't believe he is the kind of guy to do anything illegal. It is very sad, and I'd hate to benefit from his misfortune, but ironically, anything that raises further doubt about nandrolone is probably good for me.''

There are bizarre echoes of Walker's case in Richardson's downfall. He, Walker, and Cadogan were all using legitimate supplements, and endorsed them in a catalogue published by a nutrition company, Maximuscle.This advertises product containing banned substances - and an encyclopaedia on how to use steroids.

Both distanced themselves from the company long ago, but months later the brochure was still being circulated.

Triple jump world record holder Jonathan Edwards, believes that Richardson is innocent: ''But with the link between supplements and athletes who have tested positive, it was naive of Mark to continue taking the products.''

Richardson defended himself robustly: ''I followed all the guidelines and procedures, and checked everything with the chief medical officer, yet I'm still found wanting.''

The man he consulted, UKA team doctor Malcolm Brown, helped clear Diane Modahl's name - although her innocence was instrumental in bankrupting the former British governing body Scotsman Brown also believes in Walker's innocence.

Richardson says the presence of nandrolone metabolite is: ''A farce. If I do lose this year, when I've done nothing wrong and followed all the procedures, then I'll find it very difficult to come back to the sport, because I know I'm innocent.

Once you've lost your passion for anything, I think you should walk away from it, and, believe me, this is killing my passion for the sport. I would never ever take anything illegal - I wish to God I had not taken any supplements.''

The Maximuscle proprietor, Zef Eisenberg, suggested Richardson's dietary supplements could have been spiked, otherwise he reckons the positive result was caused by a flaw in test procedures.

''Mark is a fool for leaving his supplements lying around, '' said Eisenberg. ''It only takes a second to drop a capsule in something. His supplements could have been spiked at the gym. It occurs. Or he could be a fraud - I don't want that to be the case.''

Richardson said he had used an energy drink, protein supplement, and an amino-acid supplement packaged by the company before he was tested at a Slough gym on October 27.

He faces a preliminary UKA hearing a week on Friday, and if found guilty, it would bring a two-year ban from the sport and a lifetime one from the Olympics.

With UKA's anti-doping experts already having exonerated Christie, Cadogan, and Walker, it seems certrain that they will now also clear Richardson.

Like the others, he would then be summoned to IAAAF arbitration. Given the pace of Walker's case, any chance of his being cleared by the time of the Olympic Games is remote.

With impeccable timing, the UKA chief executive DaveMoorcroft was in Monaco yesterday, discussing the doping issue which again threatens to bankrupt his sport. ''I am going to ask the IAAF to take a different approach,'' said Moorcroft, who is aware of a possible further revelation soon. ''I'd like the athletes and IAAF to work together more, to set the legal processes aside and deal with the consequences, whatever they are.''

qJON Thaxton, first British boxer to test positive for nandrolone, following a British title fight in December, says he will fight a nine-month ban and #1500 fine imposed yesterday by the Boxing Board of Control.

q IVAN Gotti, twice winner of the Tour of Italy, is one of five Italian cyclists facing a two-year ban for blood doping offences. The others are Alessandro Bertolini, Gianluca Bortolami, Gianni Faresin, and Giorgio Furlan.

q FIFE Flyers' forward Daryl Ventersm has received a four-month ban from the sport's governing body, Ice Hockey UK, after a random drug test detected amphetamine.

Mark Richardson: 400m runner is willing to take a lie-detection test