The head of the World Anti-Doping Agency Dick Pound said on Wednesday he does not believe high-profile drugs positives by Americans Floyd Landis and Justin Gatlin would hinder future US Olympic Games bids.

Cyclist Landis and Olympic 100 metres champion Gatlin have tested positive for the male sex hormone testosterone. Both have denied knowingly taking banned substances.

Their positives come at a time when the US Olympic Committee (USOC) is considering whether to bid for the 2016 Summer Games.

"If you eliminated all countries where there were athletes getting positive tests, you would not have the Games anywhere," Pound told Reuters by telephone.

"If the US is seen to be making an effort to deal with the problem, that is very much in its favour, especially since it is such a leader as a country anyway."

USOC chairman Peter Ueberroth announced last week that Gatlin's coach Trevor Graham had been banned from using USOC facilities due to the "unusual number of athletes he has coached who have been convicted of doping offences".

Ueberroth and USOC Chief Executive Officer Jim Scherr have also said sending a drugs-free team to the 2008 Beijing Games was a high priority, even if it meant the team returned from China empty handed.

A USOC delegation visited Chicago on Wednesday and will tour San Francisco and Los Angeles later this week as part of its review of a potential 2016 Games bid.