Disgraced sprinter Antonio Pettigrew joined his American relay teammate Michael Johnson by planning to hand back the gold medal he won at the 2000 Sydney Summer Olympics.

Pettigrew, who admitted using performance-enhancing drugs during the Trevor Graham trial two weeks ago, agreed to return the gold the United States won in the 4x400-metres.

Pettigrew's former teammate Michael Johnson told the London Daily Telegraph on Monday that he was returning his relay gold. Johnson said he could no longer keep the medal because he now considered it to be "tainted" following Pettigrew's admission.

The 40-year-old Pettigrew also accepted a two-year ban, effective immediately, from the United States Anti-Doping Agency on Tuesday for admitting to the use of banned substances.

Pettigrew acknowledged using the prohibited substance erythropoietin, known as "EPO," and human growth hormone ("HGH"), from 1997 to 2003.

"It takes courage to accept full responsibility for such egregious conduct, and hopefully Mr Pettigrew's case will serve as another powerful reminder to young athletes of the importance of competing clean," USADA chief executive Travis Tygart said.

All of Pettigrew's competitive results since January 1997 will be disqualified. He also forfeited any medals, points, prizes and results accumulated during that span.

In addition, Pettigrew will give up his gold medals won as a member of the US 4x400 relay team at the World Championships in 1997 and 1999.

"It doesn't belong to me, so I will be returning it to the IOC because I don't want it," Johnson wrote in the newspaper. "It was not won fairly. I am deeply disappointed and saddened."