LONDON — Backup "B" sample tests came back positive for 1,500-meter gold medalist Rashid Ramzi and four other athletes accused of blood doping at the Beijing Games, an Olympic official with knowledge of the results told The Associated Press on Wednesday.

The athletes tested positive for the blood-boosting drug CERA in retests of their Beijing "A" samples earlier this year. Now, the "B" samples have confirmed the positive findings, the official said on condition of anonymity because the results are considered confidential pending a hearing.

The initial "A" sample results first were announced April 28.

The positive results clear the way for the International Olympic Committee to open disciplinary cases against the athletes, who face being stripped of results and medals and banned from the 2012 London Olympics.

In addition to Ramzi, the athletes are Italian cycling road race silver medalist Davide Rebellin, German cyclist Stefan Schumacher, Croatian 800-meter runner Vanja Perisic and Greek race walker Athanasia Tsoumeleka.

Disciplinary hearings are expected to be held at the end of the month. The IOC executive board, which has the power to disqualify athletes from past and future games, next meets in Berlin on Aug. 13-14.

Ramzi was the first gold medalist from Beijing caught using performance-enhancing drugs.

The Moroccan-born runner gave Bahrain its first ever Olympic track and field gold medal with victory in the 1,500 in 3 minutes, 32.94 seconds.

If he is stripped of the 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 would move up to the bronze medal.

Rebellin finished second behind Spain's Samuel Sanchez in the Olympic road race. If he loses his medal, Switzerland's Fabian Cancellera would move to silver and Russia's Alexander Kolobnev to bronze.

Tsoumeleka, who won the Olympic 20K walk gold in 2004, Perisic and Schumacher did not win medals in Beijing.

A sixth athlete initially was found positive in the retesting process. But the Dominican Olympic Committee cleared women's weightlifter Yudelquis Contreras last month after her "B" sample came back negative.

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.

CERA, an advanced version of EPO, increases endurance by stimulating production of oxygen-rich red blood cells.

The French anti-doping agency was the first to create a test for CERA, catching four cyclists more than two months after the end of last year's Tour de France. That success prompted the IOC to retest samples from the games.

The IOC previously disqualified nine athletes for doping at the Beijing Games. In addition, there were six doping cases involving horses in the equestrian competition.