London, Feb 21 (IANS): Two Sikh groups in Britain have demanded a full inquiry into the extent of Britain's involvement in the Indian military operation in the Golden Temple in Amritsar in 1984.

The Sikh Federation UK and the British Sikh Council said in an open letter that there were "too many serious questions that remain unanswered", BBC reported Thursday.

Sikh Federation UK's spokesperson Dabinderjit Singh said Britain's Foreign Secretary William Hague had misled parliament about the army assault on terrorists holed up in the shrine.

Citing a report by the British cabinet secretary, Hague had confirmed to parliament earlier this month that the Indian government had sought advice from Britain prior to the operation.

In his report, Cabinet Secretary Jeremy Heywood had said that Britain advised India that a military operation in Sikhdom's holiest shrine should only be a last resort and suggested that helicopters could be used as part of a strategy to minimise casualties.

Hague told Britain's members of parliament this month that the Indian government's campaign had "differed from the approach recommended" and there had been no "helicopter-borne element".

"Every single book (on the subject) says that actually helicopter gunships were used. They were used on June 4,5 and 6, 1984,” Singh was quoted as saying.

"So that starts to put a different level of complicity in terms of what parliament was told," he said.

"So not only was the foreign secretary and the report that has been produced misleading, it was not truthful."

Earlier, declassified documents suggested that the Margaret Thatcher government was involved in planning the military operation in the temple.

Official figures put the death toll in Operation Bluestar at 575.

Hague said Britain's involvement had only a "limited impact" on the events.

The British Sikh Council's Gurmukh Singh said: "Unless there is admission of the truth, and the whole truth is revealed, and then there is reconciliation, you cannot draw a line under 1984."