A mystery woman gatecrashed India's athletes' parade at the Olympic opening ceremony, Indian officials said on Sunday as they demanded answers from organizers about the apparent lack of security.

A woman in red and blue walked close to flag-bearing wrestler Sushil Kumar on Friday, in complete contrast to female members of the contingent who were wearing yellow saris and blue blazers.

"How did they allow her in? It was a security lapse. Nobody knows who she was. She looks like an Indian," Indian Olympic Association vice president Tarlochan Singh told Reuters.

"She walked along in the front line. Her dress was totally different. She was not wearing an identity card. This should have been noticed at an earlier stage but nobody bothered."

The extravagant opening ceremony, hailed around the world as a huge success, was watched by a packed 60,000 crowd in the Olympic stadium.