NATIONAL security functions will be compromised under plans to cut more than 100 civil servants from the department in charge of security vetting, the PCS union warned yesterday.

The Cabinet Office is understood to have proposed reducing the staff at UK Security Vetting to 780 full-time roles, down from its current level of just under 900.

The department vets people for sensitive Ministry of Defence and Foreign Office jobs and conducts security checks on staff applying for parliamentary passes.

Further cuts have also reportedly been proposed for the teams supporting the government’s emergency Cobra committee, including the number of staff working on chemical, biological and radiological threats.

PCS general secretary Fran Heathcote said: “We warned from the outset that plans for job cuts at the Cabinet Office failed to distinguish between back-office and front-line roles.

“It is now evident that these cuts will undermine the delivery of essential public services and compromise key government functions, including those critical to national security and emergency preparedness.

“PCS will continue to stand firmly with our members in opposing these damaging cuts. We will defend their job security and the vital work they do to keep the country running safely and effectively.”

The process is understood to be still ongoing and no final decisions on job cuts have been made.

A government spokesperson said: “We don’t routinely comment on national security staffing. More broadly, we are making the department more strategic, specialist and smaller, helping existing teams better serve the public and deliver the plan for change.”