Secret documents from the days of Margaret Thatcher's government could emerge sooner than expected after Prime Minister Gordon Brown announced on Wednesday a cut in the time taken to release official papers.

He said the existing 30-year rule on the publication of state documents would be reduced to 20 years following a review chaired by Paul Dacre, editor of the Daily Mail.

Historian Hugh Pemberton welcomed the decision, but warned that a rush of extra documents could swamp civil servants tasked with selecting important papers for the public archives.