Sussex Police has cancelled all annual leave for a month from Friday 29 March – the date when Britain plans to leave the European Union, known as Brexit.
The decision to cancel all leave was taken because of fears that Britain and the EU may not have agreed a deal.
Police chiefs are concerned that a “no deal” Brexit could lead to shortages of food, medicines and other supplies, in turn leading to public unrest or disorder.
The decision to cancel all leave means that there will be no Easter holidays for hundreds of police officers stationed in Brighton.
Good Friday is on 19 April and Easter Monday on 22 April.
Chief Superintendent Neil Honnor said: “The force will occasionally cancel days off and limit leave as a contingency for specific events, for example, New Year’s Eve or the weekend of Pride.
“Experience has shown that it is better to limit the availability of leave in anticipation of an increase in local or national demand rather than stop leave that staff have booked.
“We understand the impact of this on our staff. These restrictions remain under constant review and are done with the knowledge of our staff associations.
“We are preparing for any potential impacts on Brexit in line with national requirements.”
Sussex Police was not the first force to cancel all leave and, nationally, the government is preparing to declare the situation a “critical incident”.