Prime Minister David Cameron today said there was no evidence so far to suggest that elite British special forces played a role in the 1984 Operation Bluestar to flush out Sikh militants holed up in the Golden Temple.

"I don't want to prejudge the outcome, but I would note that so far it has not found any evidence to contradict the insistence by senior Indian army commanders responsible at the time that the responsibility for this was carried out solely by the Indian army," Cameron told parliament.

"I think it is important to put that, but it is important to get to the bottom of this," he asserted, a day after ordering an urgent probe into the decision by Margaret Thatcher's government to send a Special Air Service (SAS) officer to India to advise then Prime Minister Indira Gandhi in planning Operation Bluestar.

Cameron said the operation left "deep scars" and "incredibly strong feelings that exist to this day".

Cameron has asked Cabinet Secretary Jeremy Heywood to conduct the investigation after documents declassified suggested the British special forces officer advised the Indians on carrying out the attack.

The premier's spokesman said the investigation will examine two issues - British action in 1984 and the decision to release such sensitive government papers.

Labour MP Tom Watson and Lord Indarjit Singh had demanded an explanation after documents made public over the New Year indicated that the officer of Britain's SAS was dispatched to help India plan for the raid on the Golden Temple, an operation that left over 1,000 people dead.

The documents being referenced were released by the National Archives in London under the 30-year declassification rule as part of the series over the New Year.

Five months after Operation Bluestar, Gandhi was assassinated by her Sikh bodyguards in retaliation for the raid on the Golden Temple.