The Commonwealth Games was plunged into a new crisis on Monday after women's track 100m gold medal winner Osayemi Oludamola of Nigeria failed a drugs test.

Commonwealth Games Federation president Mike Fennell said the 24-year-old, who was promoted to gold when Australia's Sally Pearson was disqualified for false-starting, tested positive for the banned stimulant methylhexanamine.

"As far as anti-doping is concerned we have conducted over 950 tests to date and we've had results from just over 700," said Fennell.

"Unfortunately I have to report to you we have had a positive result.

"This result was in relation to the winner of the women's 100m final, Ms Osayemi from Nigeria. She has been notified in accordance with the anti-doping standard that applies to these Games."

Oludamola requested her B sample be tested with an official statement from organisers later Monday saying the results were expected "within 48 hours" and that she would remain suspended until then.

It was the first positive test of the Games, now in their eighth day of competition, and Fennell said it remained to be seen how much damage it would do to the image of the sport given it came in such a high-profile event.

"Any positive test, whether in a high-profile event or not, is something we very much regret because we all strive for a clean Games and a clean sport," said Fennell.

"We don't know what sort of damage will accrue but we want to let everyone know that we are very vigilant and we are doing all we can to eliminate doping in sport."

Organising committee secretary general Lalit Bhanot said the positive test showed no-one could get away with cheating.

"We want dope-free games, he said. "That's why 1,500 tests are being conducted. If someone is caught, action will be taken as per the rules.

"At the same time it is a message to everyone that no one can escape."

If Oludamola is stripped of her medal, then Natasha Mayers of St Vincent and The Grenadines would be promoted to first with England's Kathryn Endacott taking silver and Bertille Atangana of Cameroon coming third.

Nigerian news website Vanguard quoted Athletics Federation of Nigeria president Solomon Ogba as saying Oludamola was given prescription medicine to fight a nagging toothache.

"She took medication for her toothache and we strongly suspect that it was that, which led to her failed drug test," he said, adding that they were fighting the case.

Despite the positive result from Thursday's final, Oludamola competed in the 200m heats on Sunday, but finished fourth to narrowly miss the final.

That medal race was due to be held Sunday evening but was postponed after more chaos when Elena Artymata of Cyprus, the fastest qualifier, was disqualified from her semi-final for stepping out of her lane.

She appealed but it was turned down. However, it became too late to hold the race which will now be run later Monday.

The 100m final had already been controversial after Pearson, who was first over the line, was stripped of her gold for a false start after a chaotic chain of events.

She was forced to endure an agonising wait for the outcome of a series of protests and eventually had her medal taken away hours later despite being taken to the medallists' waiting room.

Fennell later blasted the inexperienced organisers at the track venue for handling the situation badly.

England's Laura Turner of England was also disqualified for a false start and if Oludamola's medal is taken away then it would mean only five athletes would be classified from the eight who started the race.