Key transport staff in London are being refused leave amid fears of fuel shortages and possible riots if Britain crashes out of the EU.
Managers and workers in Transport for London's high tech control room are being put on alert for three weeks from March 23rd.
The vital Network Management Control Centre oversees London's bus network and many of the capital's main roads.
A leaked email seen by ITV News warns of 'risks associated with border disruptions, fuel and public disorder' if Britain leaves the EU without a deal.
Sources suggested a combination of panic buying at petrol stations, long delays at airports and street protests could cause serious congestion.
Around 150 control room staff have been told requests for leave between March 23rd and April 14th will be turned down.
A TfL spokesperson said: