MARGARET Thatcher's UK Government had a secret blacklist of Scottish nationalists, newly released documents reveal.

Whitehall departments worked with MI5 in the 1980s to identify 1420 "subversive" civil servants, who were monitored and had promotions blocked.

Papers released at the National Archives show that 35 of those on the blacklist were listed as "Welsh or Scottish nationalists", "black or Asian racial extremists" or "anarchists".

The documents also link 25 people working within the Scotland Office to communist and socialist groups.

MI5 bemoaned that it was unable to list the "subversives" within the NHS without risking the investigation becoming public knowledge.

The documents say: "Departments should identify their key areas and develop procedures to ensure as far as possible that subversives are not posted there.

"It might be possible covertly to move individuals to posts where they would have less potential for disruption.

"At higher levels, one or two departments do have covert systems to enable them, if necessary, to take these problems into account before promotions are decided."

The Cabinet Office initially refused to confirm or deny whether such blacklists were still in use, after the practice was revealed.

A spokesperson has now said: “The inter-departmental group on Subversion in Public Life (SPL) is no longer in operation and there is no other unit conducting similar work.”

Also on the blacklist were 733 people listed as Trotskyists, 607 as communists and 45 as fascists.

At the Ministry of Defence, the SPL reported that there were "111 subversives", with many at the Rosyth dockyard.

MI5 held similar lists for suspect local councillors and active trade unionists.