British military advice was given to the Indian authorities ahead of the 1984 massacre at the Golden Temple in Amritsar but it had a "limited impact" on the operation which resulted in up to 3,000 deaths, a Government investigation has concluded.
The investigation was ordered after documents released under the 30-year rule suggested that an SAS officer advised the Indians about how to deal with the Sikh dissidents occupying the site.
Foreign Secretary William Hague told the Commons that a British adviser travelled to India in February 1984, but his recommendation for a surprise assault using helicopters was not reflected in the raid which took place in June that year and resulted in extensive bloodshed.
Mr Hague said: "The Cabinet Secretary's report finds that the nature of the UK's assistance was purely advisory, limited and and provided to the Indian government at an early stage; that it had limited impact on the tragic events that unfolded at the temple three months later; that there was no link between the provision of this advice and defence sales and there is no record of the (British) government receiving advance notice of the operation."
The investigation, by Cabinet Secretary Sir Jeremy Heywood found that Margaret Thatcher's government agreed to a request from the Indian authorities to provide advice on the situation.
Mr Hague said: "(Sir Jeremy) has established that a single British adviser travelled to India between 8-17 February 1984 to advise the Indian intelligence services and special group on contingency plans that they were drawing up for operations against armed dissidents in the temple complex including ground reconnaissance of the site.
"The adviser's assessment made clear that a military operation should only be put into effect as a last resort when all attempts at negotiation had failed.
"It recommended including in any operation an element of surprise and the use of helicopter-borne forces in the interest of reducing casualties and bringing about a swift resolution."
In June that year the Indians launched Operation Blue Star, which resulted in 575 deaths according to official figures but Mr Hague said other reports suggested "as many as 3,000 people were killed including pilgrims caught in the crossfire".
"This loss of life was an utter tragedy," the Foreign Secretary said. "Understandably members of the Sikh community around the world still feel the pain and suffering caused by these events."
Mr Hague said the Indian plan "changed significantly" between February and June 1984, with a considerably larger dissident force and extensive fortifications within the temple complex.
After the UK adviser's visit the Indian army took over responsibility for the operation, and the "main concept" behind it changed.
Sir Jeremy's report contained an assessment by current military staff comparing Operation Blue Star with the approach recommended by the unnamed adviser.
Operation Blue Star was a ground assault, without the element of surprise or helicopter-borne troops.
"The Cabinet Secretary's report therefore concludes that the UK military officer's advice had limited impact on Operation Blue Star," Mr Hague said.
Sir Jeremy's investigation involved searching 200 files and 23,000 documents, Mr Hague said, but the Ministry of Defence's papers on the advice given to the Indians had been destroyed in 2009.
But copies of some of the destroyed documents were contained in other departmental files and "taken together these files provide a consistent picture of what happened".
Conservative MP Paul Uppal, who is of Sikh origin, told BBC Radio 4's The World At One: "I think the British Sikh community will be relieved that British involvement was purely advisory, that the British government had no further involvement in any subsequent Indian military action, and also heartened by the fact that this report has been speedy, it's been transparent and conducted in a rigorous manner.
"I think their overall impression will be one of comprehension but relief that any involvement was purely of this one officer in an advisory capacity.
"There will always be groups that have issues and highlight these sorts of things, but the important point is that it now transpires that military operations were only advised to be seen as a last resort if political means were exhausted."
Mr Uppal repeated his call for full disclosure of documents relating to the incident. Asked if there was a need for an apology, he said: "What I would like to see is Sikh organisations and the Indian High Commission to work with fellow parliamentarians to start a process of truth and reconciliation so that finally, after 30 years, victims and families can finally start to feel a sense of justice."