Secret plans to protect Tony Blair from a terrorist attack were left in a hotel, it was claimed today.
They were part of a folder which lists ways in which assassins could try to kill the Prime Minister and other members of the Cabinet, it was alleged.
It includes suggested "attack scenarios" including car bombs, mortar attack, rocket grenades and suicide bombers.
The dossier covers security arrangements for the forthcoming Labour Party conference in Manchester in September.
It was left in the Midland Hotel in the city, around the corner from the conference centre.
It was handed to a newspaper, The North West Enquirer, which handed it to Greater Manchester Police.
It is not clear how much of a security blunder release of the the details could be.
The documents were stamped "Restricted" and "Confidential", but Greater Manchester Police said security had not been compromised and no specific threat against the conference or the Prime Minister had been identified.
The information is from a variety of sources dealing with security arrangements for the conference.
A number of different agencies had taken part in the planning and it was not yet known which one had left the dossier in the hotel.
A force spokeswoman said it was not a member of Greater Manchester Police.
Yesterday, the force's anti-terrorism squad carried out a series of raids across the city as part of an investigation into suspects allegedly supporting terrorism in Iraq.
In 1996 Manchester's Arndale centre was bombed by the IRA and the same group killed five in an attack on the Tory Party conference in Brighton in 1984.
A GMP spokeswoman said: "Officers are confident that the folder does not belong to a member of GMP staff and are currently talking to partners to establish how the file was misplaced.
"This is a major security operation involving many agencies and a great deal of planning and information sharing is inevitably involved in dealing with an event of this scale.
"The information which police share with other agencies is risk assessed and the documents in this folder were of a level deemed safe to share with partners.
"Greater Manchester Police take all information and intelligence about security issues extremely seriously.
"There is no intelligence to suggest that this event is a specific target for terrorists. However we are conscious of the fact that the city has been targeted in the past so we need to remain vigilant and it is only right that we have contingency plans in place to deal with all manner of eventualities."