Labour MPs accused Foreign Secretary William Hague yesterday of dodging the full truth about Britain's connections to the bloody 1984 massacre of thousands of Sikhs in Amritsar.

Mr Hague told the Commons that an inquiry by Cabinet Secretary Jeremy Heywood had concluded that Britain's "assistance" to the Indian government was "purely advisory and limited."

The tame probe was launched last month amid an outcry over documents released under the 30-year rule, which revealed that an SAS officer was sent to advise Indian military authorities in the run-up to their attack on Sikhs occupying the Golden Temple.

Mr Hague told MPs that the Cabinet Secretary had found "no evidence" that British military advice was linked to commercial and trading considerations, and "no evidence" that Parliament had been misled.

However the wily Foreign Secretary did confess that some military files were destroyed at the Ministry of Defence in November 2009, including one file on military advice to the Indian authorities.

He claimed that "at least some" of the destroyed files were found in other departmental files.

Mr Hague admitted that this raised "sufficient questions" to justify a further investigation into how documents were released by government departments under the 30-year rule, and the revised 20-year rule which will operate from 2022.

A new review, including "the processes for withholding information," would be carried out by Alex Allan, the Prime Minister's independent adviser on ministerial standards.

Mr Hague claimed that the government wanted to be as open as possible "insofar as that does not undermine the principle upheld by successive British governments of not revealing any information relating to intelligence or special forces."

Labour MP Tom Watson strongly challenged Mr Hague's statements and demanded a full apology from the government for the way Sikhs were "misled" in 1984.

Documents showed that a march to commemorate the thousands of massacred Sikhs was banned "in view of the importance of the British political and commercial interests at stake."

Left MP John McDonnell commented sharply that Britain's Sikh community would not be reassured by the fact that the government provided military support to desecrate the holy Golden Temple.

Mr McDonnell demanded "a full, public and independent inquiry."