The gold medal may be safely packed away in their luggage, and the drug tests may have come back clean.

But any cheat clever enough to outwit the unprecedented anti-doping regime put in place for the 2012 London Olympics will be spooked by the knowledge that for the next eight years they will be looking over their shoulder.

In accordance with the World Anti-Doping Agency guidelines, samples taken from athletes competing in London will be stored for years afterwards to allow for anti-doping technology to catch up.

This policy of retrospective testing has operated with success for several years, most notably when 2008 Olympic 1,500 metres gold medallist Rashid Ramzi of Bahrain was stripped of his title in November 2009, a year after crossing the finish line at the Bird's Nest Stadium in Beijing.

Yet this policy has been given added potency for the London Games, where advances in technology will allow for so-called "data-mining" of test results -- the capture of a complete profile of an athlete's sample.

As London 2012 organiser Lord Sebastian Coe has repeatedly emphasised in the build-up to the Games: "You come to London and you try to cheat, we will get you."

The scientists tasked with ensuring that Coe's strident warning is not empty rhetoric are already busy at work at an unprepossessing concrete building on an industrial estate just outside Harlow in Essex, northeast of London.

"This is the first time at a Games where we are using a total capture of data," said Professor David Cowan, director of the drugs control centre at King's College London, who is heading the laboratory.

"That will enable us to review the data, sometimes within a 24-hour period, where we can look for things that we have not previously encountered.

"So although we'll be looking for 200 designated substances that have been banned, our total data capture will allow us to do a 'data-mining' approach for otherwise unknown substances."

Cowan is confident the enhanced techniques being used in London will deter athletes from using banned substances.

"Where the athletes know there is going to be good testing, they won't take drugs -- the deterrent effect is very effective and that will enable athletes to compete fairly in London," Cowan said.

Kerry O'Callaghan, a spokeswoman for GlaxoSmithKline, the pharmaceutical firm providing the technology that will separate and analyse samples said the testing process was now faster than ever.

"One piece of equipment here can analyse 60 samples in one go and actually looks for 60 different substances," she told AFP.

"Where a previous test would take 40 minutes to run, it now takes 14 so all of these things have been done to improve the speed and the efficiency of the operation."

Cowan said: "At these Games we're going to be analysing more than 6,000 samples and at a peak we may have as many as 400 samples coming through in a day."

British high jumper Samson Oni is one of the thousands of athletes who hopes to benefit from the levelling of the playing field that London's anti-doping program is striving to achieve.

Oni, an ambassador for London 2012's "Win Clean" campaign, has mixed feelings however about allowing athletes who have previously been found guilty of doping back into the Olympics.

Sprinter Dwain Chambers, who served a ban for doping earlier in his career, will hear in April whether the Court of Arbitration for Sport has overturned a British Olympic Association ruling that drug cheats cannot compete at London 2012.

Oni told AFP: "I used to say that if you've been caught then you should be banned because at the end of the day I'm a clean athlete and I want to compete with other clean athletes and if I don't compete with other clean athletes then it's my hard work going down the drain.

"But at the same time I also understand what other people are saying which is that if you've done your time then you can come back."