Bahrain's first Olympic track and field gold medalist, an Italian cycling silver medalist and a prominent German cyclist are among the six athletes caught for blood doping in retests of their Beijing samples.

National sports bodies in Bahrain, Italy and Germany confirmed Wednesday that 1,500m champion Rashid Ramzi, road race medalist Davide Rebellin and rider Stephan Schumacher had tested positive for the new blood-boosting drug CERA.

A person with knowledge of the results told The Associated Press that Greek race walker Athanasia Tsoumeleka and Croatian 800m runner Vanja Perisic were the other track athletes who tested positive.

The Dominican Olympic Committee identified women's weightlifter Yudelquis Contreras as the sixth athlete. She competed in the 53km category as Yudelquis Maridalin and finished fifth.

If their backup "B" samples also come back positive, the athletes face being disqualified, stripped of medals and banned from the next Olympics.

The International Olympic Committee announced on Tuesday that a total of seven positive tests involving six athletes came back positive for CERA, which increases endurance by stimulating production of oxygen-rich red blood cells.

The IOC has not named the athletes or the sports involved.

The six new cases bring to 15 the total number of athletes caught doping in Beijing, and underscore the IOC's aggressive policy in catching drug cheats even outside the period of the Olympics.

The IOC reanalysed a total of 948 samples from Beijing after new lab tests for CERA and insulin became available following the Olympics. The testing began in January and focused mainly on endurance events in cycling, rowing, swimming and track and field.

Ramzi is the first Beijing gold medallist caught positive for performance-enhancing drugs. The Moroccan-born runner, who won the 800-1,500 double at the 2005 world championships, gave Bahrain its first ever Olympic track and field gold medal with victory in Beijing in 3 minutes, 32.94 seconds.

Ramzi's "B" sample will be tested in France on June 8 and he will face an IOC hearing the same day, the Bahrain Olympic Committee said.

"The Bahrain Olympic Committee apologizes for receiving such news from the International Olympic Committee since it ensured Ramzi went through all the necessary doping tests before the games and they were all negative," the committee said in a statement.

Ramzi became a citizen of Bahrain after moving to the Gulf nation to take up a job in that country's armed forces in 2002, but retains a Moroccan passport and trains with old coach Khalid Boulami.

If he is stripped of the Beijing victory, Asbel Kipruto Kiprop of Kenya stands to be upgraded from silver to gold. Nicolas Willis of New Zealand would go from bronze to silver, and fourth-place finisher Mehdi Baala of France could move up to the bronze medal.

The International Association of Athletics Federations confirmed it had received notification of three cases in track and field, but declined to give any names because they were considered confidential.

"The IAAF must wait for further details from the IOC before considering any provisional suspension of the athletes and a decision is not expected within the next week," the IAAF said in a statement.

However, the person with knowledge of the results identified the two others as Tsoumeleka and Perisic. The person confirmed their identities to the AP on condition anonymity because the names haven't been released by the IOC.

Tsoumeleka finished ninth in the 20km, and Perisic was eliminated in the first-round heats of the 800m.

Tsoumeleka announced in January that she had tested positive in Beijing rechecks. She was charged by a Greek prosecutor earlier this month with using banned drugs. In Rome, the Italian Olympic Committee suspended Rebellin and anti-doping prosecutor Ettore Torri called him to a hearing on Monday. If he loses his medal, Switzerland's Fabian Cancellera could move to silver and Russia's Alexander Kolobnev to bronze.

Rebellin's pro cycling team, Diquigiovanni-Androni, temporarily suspended the rider, pending analysis of the "B" sample. The German cycling federation announced that Schumacher, who finished 13th in the Beijing time trial and dropped out before the finish of the road race, was among the positive cases.

The International Weightlifting Federation said it had been notified by the IOC of a positive case, but declined to name the athlete or country involved.

AP