By Jack Stubbs and Mark Trevelyan

RIO DE JANEIRO (Reuters) - Athletes with past doping convictions should not be on Team USA, Olympic breaststroke champion Lilly King said on Monday in response to a question about the inclusion of sprinter Justin Gatlin.

King beat Russian Yulia Efimova to win the women's 100 meters breaststroke gold medal, a day after publicly criticizing her rival, who has served two previous doping-related suspensions.

She was then asked at a news conference if Gatlin, who also has two past offences, should be taking part in the Rio Games.

"Do I think people who have been caught for doping offences should be on the team? No, they shouldn't," she told reporters at a tense news conference alongside Efimova.

Gatlin tested positive in 2001 for an amphetamine contained in a medication he had taken for attention deficit disorder (ADD). The 2004 Olympic gold medalist and 2005 world champion then failed a test for the banned steroid testosterone in 2006.

Revelations of state-sponsored doping in Russia have dominated the build-up to the Rio Olympics and increased pressure on athletes and officials to take a stand on the divisive issue.

(Editing by Peter Rutherford)