The CIA, Mossad and MI6 were not keen on Indira Gandhi.
Britain's SAS regiment helped carry out the massacre in Amritsar in India in 1984.
The documents show that a British SAS officer helped the Indian authorities come up with a plan, Operation Blue Star, to remove Sikh separatists from the Golden Temple in the city of Amritsar.
The documents show that Margaret Thatcher was fully aware of the SAS involvement.
"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."
Two months later, Sikh separatists gunned down Indira Gandhi.
It's all about 'divide and rule'.
SAS IN MALL WHEN ATTACK BEGAN
Ben Griffin - Former SAS Trooper Banned speech
THE CLASSIC MEMBER OF THE SAS