Six hundred council workers are refusing to relocate unless safety screens are installed in their new offices.
Staff at Greenwich Council in south London are boycotting the proposed office move because there are no safety screens in the reception area at the new premises.
Public sector union Unison said it was concerned for staff safety after two recent violent incidents involving receptionists.
Onay Kasab, Greenwich branch secretary, said reception staff were at risk from angry members of the public.
"Members of the public get angry and it’s the reception staff who bear the brunt," he said.
The council said they would introduce a security guard and CCTV to improve safety in the new offices in Woolwich.
The council is due to move to the new premises by February of next year.