Whitehall mandarins have been told to work from home next week. They are unlikely to be able to reach their offices because of the security surrounding President George Bush's visit.
Civil servants, including Tony Blair's advisers, have been warned of serious disruption, which will make it very difficult for them to get to work.
A leaked internal memo has warned senior civil servants, who have been cleared to work for ministers after security checks by the police and M15, that they may be frisked by police.
The disruption has caused dismay in Whitehall among staff who complain that they will have to cancel meetings and be unable to do their work.
"We won't be able to have anyone in the building or carry out our meetings or even get to work. It's a serious nuisance," said one civil servant.
A memo sent to Cabinet Office staff warns of disruption caused by demonstrations and "the President Bush vehicle entourage requesting cleared secured vehicle routes around London and the security cordons creating a sterile zone around him".
It says staff and contractors working on buildings will face a big "disruptive impact" next Wednesday and Thursday and work may need to be cancelled. It advises civil servants that they will find it extremely difficult to get to work unless they come in very early and then the police may "wish to search any baggage you carry".
The demonstations will also affect the ability of ministers to receive briefing papers by courier and to travel from their offices to Parliament.
The memo says: "Staff should consider working at home if possible or plan to get into work as early as possible - consider arriving before 8am." Staff working on secret projects will have to set up secure electronic links from their homes.Reuse content