Pest controllers were called to an office in Kennington, south London, used by weapons and technology experts at the Metropolitan Police after reports of 'mice everywhere'.
According to internal police reports, a family of mice even set up home in one police worker's desk - burying themselves in his paperwork.
The report reminds workers of 'the Met's clear desk policy' - meaning everything on your desk must be filed away by the end of each day so cleaners can do their jobs.
It states: "Employees came across a number of mice at a police building.
"Action was taken to remove the mice from the premises and there have not been any sighting of mice since."
A spokeswoman for the Met said that the 'paperwork home' set up on one desk by mice consisted of 'paperwork that did not relate to operational police matters'. ...