Blood doping, a scourge in world sports since the scandal-hit 1998 edition of the Tour de France cycling classic, will not help athletes to glory at next month's Olympic Games in Athens, experts say.

"If you cheat, you will be caught," Dick Pound, chairman of the World Anti-Doping Agency (WADA), wrote in the agency's Play True newsletter.

Swede Arne Ljungqvist, who heads the International Olympic Committee's (IOC) medical commission, echoed Pound's confidence that blood-doping cheats would be caught, saying testing would increase in Athens during the August 13-29 Games.

"All ways of enhancing the performance capability by increasing the number of red blood cells are well covered by anti-doping laboratories," Ljungqvist told Reuters in a recent interview.

Blood doping can boost athletes' performance, especially in endurance disciplines such as long-distance running, swimming and cycling.

Substances and methods that artificially increase the number of red blood cells, which carry oxygen to muscles, are banned.

Athletics sprint world champion Kelli White of the United States was suspended for two years in May after admitting she had used the blood-boosting synthetic hormone erythropoietin (EPO) as well as prohibited muscle-building anabolic steroids.

The International Swimming Federation (FINA) decided in November 2002 that all swimmers who break world records must undergo tests for EPO. The move followed complaints from some top swimmers about the lack of tests.

GOLD MEDALS

Earlier that year, cross-country skiers Johan Muehlegg of Spain and Russians Larisa Lazutina and Olga Danilova were caught for blood doping and lost the gold medals they had won at the Olympic Winter Games in Salt Lake City in the United States.

In July 2001, Russian long-distance runner Olga Yegorova tested positive for EPO and earlier that year six Finnish skiers were found guilty of blood doping at the world championships on home snow in Lahti.

The Tour de France introduced tests for EPO in 2001 after the "Tour of Shame" three years earlier which was rocked by police raids and led to the Festina trial in which Richard Virenque and his team mates alleged that doping was widespread in cycling.

It is not often mentioned in Swedish newspapers, but the first Olympic athlete to test positive for any sort of doping was a Swede -- pentathlete Hans Gunnar Liljenwall for alcohol use at the 1968 Mexico City Games.

More than 50 Olympic competitors have been caught since then, with athletes hungry for glory, prize money and lucrative sponsorship contracts and aided by unscrupulous coaches and physicians often a step ahead of the IOC's medical commission.

Seven competitors were caught for using banned substances at the 2000 Sydney Olympics, though none was implicated in blood doping -- prompting some commentators to speculate that the cheats might have found a new generation of undetectable blood-boosting drugs.

"The prohibited substances and methods than can increase the (red blood cell count) are myriad," Peter Symons, a veterinarian involved in anti-doping work at the Sydney Olympics and adviser to the Athens 2004 organisers, wrote in a research report.

He said road cycling and cross-country skiing were among the toughest of all endurance sports.

IMPROVED ENDURANCE

"Logically, athletes in these sports have the most to gain from an increase in their aerobic capacity. This creates a temptation to use the variety of prohibited substances than can increase their red-cell mass," Symons said.

Mats Garle, head of the doping control laboratory at Huddinge University Hospital in Sweden, agreed, saying scientific research showed that blood doping could improve endurance by up to 10 percent.

"It's clearly the most efficient of the illegal ways to enhance performance," he told Reuters in his high-tech laboratory -- one of 32 international doping test sites accredited by the WADA.

Haemoglobin-based oxygen carriers (HBOCs) have been named by many experts, including Symons, as possible performance boosters but Garle said modern laboratories were equipped to detect them.

"We already have the analysis to trace the substance. The question now is how many tests we will do during the Olympics this summer," he said.

"The requirements on tests get tougher and tougher, making the tests more expensive."

WADA, which faced a budget squeeze last year, carried out just over 2,700 doping tests, of which some 300 were blood tests, before and during the Sydney Olympics.

"In Athens this year the number will increase even more," said Ljungqvist.