Hague briefed members of the British Parliament on assistance given to the Indian government in a 1984 effort to take on militants in the so-called Golden Temple, Sikhs' holiest shrine.
"The British High Commission in India recommended that the government respond positively to the request for bilateral assistance, from a country with which we had an important relationship," he said in his remarks Tuesday. "This advice was accepted by the then-government."
Hague said the three-day siege, Operation Blue Star, left "as many as 3,000" people dead, including religious pilgrims caught in the cross-fire.
"This loss of life was an utter tragedy," he said.
Hague said the results of a Cabinet-level investigation found the British role in the attack was "purely advisory" and had a "limited impact" on events that unfolded in India in the aftermath of the Golden Temple raid. British assistance to India was provided "at an early stage," he added.
The BBC noted Indian Prime Minister Indira Gandhi was assassinated by her Sikh bodyguards after the attack. Anti-Sikh riots that gripped India after the assassination left as many as 3,000 people dead.