The woman who appeared in India's Olympic contingent in the opening ceremony was a cast member in the event, London 2012's Seb Coe has said.
She was a cast member who got "slightly over-excited", he told journalists at the daily Olympic news conference.
Indian team officials were angered by the woman's presence and are seeking an apology.
She became known as "the woman in red" because of the colour of the top she was wearing.
Lord Coe said: "We have been looking at security but she didn't just walk in off the street. She was a cast member who got slightly over-excited.
"She shouldn't have been there but she clearly started in that venue. I will be speaking to the Indian delegation."
In contrast to the Indian team's yellow saris or blue blazers, her red top made her stand out as she walked next to India's flag-bearer, wrestler Sushil Kumar.
"This was bizarre. We will ask for an apology," India's chef de mission, PKM Raja, told the Times of India.
"The Indian contingent was shown for just 10 seconds and to think this lady hogged all the limelight."
He added: "When we were entering the stadium, a member of the organising committee or some security guy asked to be in front of us. We thought the woman was part of Locog.
"When we entered the stadium, the woman who was walking between us and the contingent ahead of us, the Independent Olympic Athletes, suddenly came back and started walking next to Sushil Kumar, our flag-bearer.
"We are totally surprised by the manner in which she joined the delegation and kept walking inside the stadium," he said.
He told the newspaper that he was not sure of the woman's nationality.
He said the woman "embarrassed us in front of the world".
Several newspapers claim to have identified the woman in question as a post-graduate from Bengaluru, India. However this remains unconfirmed.
India is fielding 81 athletes at the London Games, with medal hopes in archery, boxing, badminton, shooting, tennis and wrestling.
Olympic organisers Locog have said they will release a statement shortly.