The US 4x400m relay team that won gold at the Sydney Games in 2000 have been stripped of their medals after Antonio Pettigrew admitted to doping, the International Olympic Committee (IOC) said on Saturday.

It was the sixth American medal from the Sydney Games lost to doping in the past eight months after US sprinter Marion Jones [Images] was stripped of her five medals due to her doping confession last year.

Reallocation of the medals was not discussed at the IOC's executive board meeting in Beijing [Images], communications director Giselle Davies told reporters.

• Marion Jones: Glory gone

"It was decided that the entire US relay team will be disqualified from the Sydney Games," Davies said.

She said the reallocation of the medals, including Jones's, would be decided once an ongoing investigation into the San Francisco-based Balco laboratory, responsible for providing top athletes with drugs, is complete.

"It forms part of a wider piece of work...on the Balco case," Davies said, adding that issues such as medal reallocation arising from Balco would be resolved as one big case rather than on an individual basis.

The Nigerian quartet finished second at the Sydney Games with Jamaica third and the Bahamas fourth.

Former world 400 meters champion Pettigrew, now retired, admitted in May during the trial of former coach Trevor Graham that he had used performance-enhancing drugs for about six years.

His admission has led to US Olympic champion Michael Johnson to say he was returning his Sydney Games relay gold medal after he felt he had not won it legitimately. The Sydney 2000 Games gold-winning relay team included Johnson and twins Alvin and Calvin Harrison.

JOHNSON DISAPPOINTED

Johnson had won five Olympic gold medals but said in an interview recently he now had to be known as a four-time Olympic gold medallist.

Jerome Young, who ran in the Sydney preliminary rounds, had already been stripped of his medal due to a doping offence while Angelo Taylor was also awarded a gold.

The United States Anti-Doping Agency has annulled all Pettigrew's competitive results since January 1997 and has said the athlete had also voluntarily surrendered his 2000 Sydney Olympics [Images] 4x400 meters relay gold medal and his 1997 and 1999 world championship relay golds.

The decision could lead to the US team also losing their 4x400 meters world record of 2:54.20 set in July 1998.

Pettigrew ran that race with Jerome Young, Tyree Washington and Johnson. He won his individual world title in Tokyo in 1991.

Pettigrew acknowledged using the prohibited blood booster erythropoietin (EPO) and human growth hormone (HGH) beginning on or about January 1997 through 2003.