NEW YORK: Disgraced sprinter Tim Montgomery has admitted using performance-enhancing substances before running in the triumphant US 4x100m relay team at the 2000 Sydney Olympics.

Montgomery, in jail having been sentenced to almost nine years imprisonment on heroin charges and for a check fraud, made the admission in an interview for the HBO TV show "Real Sports with Bryant Gumbel" scheduled to be broadcast on Tuesday.

"Prior to the 2000 Olympic Games in Australia I broke the rules," said Montgomery, 33, in a transcript provided by HBO.