Lt Gen Kuldeep Singh Brar, the general in charge of the successfulraid on the Golden Temple in Amritsar in 1984, has dismissed claims that the UK colluded in the operation, the BBC reported today.
Gen. Brar told the BBC that there was 'no question' the Thatcher administration advised Delhi.
The dispute comes after Labour MP Tom Watson said he had seen declassified documents suggesting that Margaret Thatcher responded positively to an Indian government request for advice on planning the 1984 attack and sent an officer from the SAS special to help draw up a plan.
Watson cited two letters that have only just been released under the 30-year rule.
However, British Prime Minister David Cameron has ordered an urgent investigation in to the allegation. Cameron yesterday asked Cabinet Secretary Sir Jeremy Heywood, Britain's most senior civil servant, to look into the case and report back to him.
The storming of the Golden Temple, codenamed Operation Blue Star, was carried out to flush out Sikh separatists.
Gen Brar, one of the architects of the operation, told the BBC's Newshour programme on Tuesday that it was the work solely of military commanders in India.
"I am dumbfounded and totally amazed," he said. "I do not believe that these documents could be authentic'', head adding that "as far as I am concerned the operation was planned and executed entirely by military commanders of the Indian army.
"There was no question of our getting help or advice from any foreign country - and certainly not from Britain - so as far as I am concerned (these allegations) appear to be like fiction," the 79-year-old former general said.
The BBC reported Brar as saying that he "could not imagine" any scenario whereby covert UK support was supplied to the Indian prime minister at the time of the storming of the Golden Temple without his being unaware of it.
The request for British advice is disclosed in a letter, marked "top secret and personal" and dated 23 February 1984, from the Foreign Office to the Home Office.
The letter said: "The Indian authorities recently sought British advice over a plan to remove Sikh extremists from the Golden Temple in Amritsar.
"The Foreign Secretary decided to respond favourably to the Indian request and, with the Prime Minister's agreement, an (SAS) officer has visited India and drawn up a plan which has been approved by Mrs Gandhi.
"The Foreign Secretary believes that the Indian Government may put the plan into operation shortly."
According to reports, about 400 people were killed in Operation Blue Star in June 1984 - including 87 soldiers.