LONDON — Bahrain’s first Olympic track and field gold medalist, an Italian cycling silver medalist and a Dominican weightlifter are among the six athletes caught for blood doping in retests of their Beijing samples.

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

German sports officials confirmed the same was true of prominent rider Stephan Schumacher, and the Dominican Olympic Committee identified women’s weightlifter Yudelquis Contreras as another of the athletes snared by the retests. She competed in the 116-pound category as Yudelquis Maridalin and finished fifth.

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

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 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 reanalyzed 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 medalist 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 20-kilometer walk, and Perisic was eliminated in the first-round heats of the 800.

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.

The 37-year-old Rebellin finished second behind Spain’s Samuel Sanchez in the Olympic road race. 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.

“I don’t see why I should take a path that would ruin me or my image,” Rebellin told Italy’s state TV on Wednesday. “I don’t know if I’ll still be able to race, but I will always ride because cycling is my life.”

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 27-year-old Schumacher already has been banned for two years by the International Cycling Union after being caught by French authorities in retesting of Tour de France samples for CERA.

Schumacher won two individual time trial stages at the Tour de France last July and wore the yellow jersey for two days as race leader.

“Before we do anything we are waiting for the riders to say if they wish to open the ’B’ samples,” said International Cycling Union president Pat McQuaid. “One of the riders (Schumacher) is already under suspension and, for the other one, (Rebellin) we will be writing to him and suspending him provisionally.”

The IOC previously disqualified nine athletes for doping at the Aug. 8-24 Olympics. In addition, there were six doping cases involving horses in the equestrian competition.

The IOC has already stripped four athletes of Beijing medals — Ukrainian heptathlete Lyudmila Blonska (silver), Belarusian hammer throwers Vadim Devyatovskiy (silver) and Ivan Tsikhan (bronze) and North Korean shooter Kim Jong Su (silver and bronze).