An unnamed Indian track and field athlete has tested positive for the banned steroid nandrolone at the Commonwealth Games in Delhi.
The athlete is the third to fail a drugs test after two Nigerians tested positive for a banned stimulant.
Damola Osayemi has subsequently been stripped of her 100m title.
Games Federation president Mike Fennell says he cannot name the Indian athlete until he is sure the person has been notified of the positive result.
Of the 1,300 tests carried out in Delhi, there have been three positive tests, said Fennell.
"It's very unfortunate," Lalit Bhanot, secretary general of the local organising committee, told a news conference. "We tried our level best. Not only the federations but also the National Anti Doping Agency (NADA) tried with our out-of-competition tests.
"The government is very serious about these things. One can't be controlled if the person is trying to take some forbidden substance to enhance their performance."
Damola Osayemi was stripped of the women's 100m gold medal on Tuesday after her B sample confirmed a positive test for methylhexaneamine.
Fellow Nigerian Samuel Okon, who finished sixth in the 110m hurdles final, also tested positive for the drug. He waived his right to a B sample tested and was disqualified.
India has performed well in track and field at this year's Games, and on Tuesday night the country won only its second ever gold on the track when the women's 4x400m relay sprinted to victory.
On Monday, discus thrower Krishna Poonia became the first Indian woman to win a Games track and field title.
It is not known whether the athlete who tested positive is one of India's medal winners.