Police were called to a security alert at Sinn Fein MLA Pat Sheehan's office in Belfast on Friday night.
Officers and a police explosives dog were sent to Mr Sheehan's office on the Springfield Road after receiving a call that suggested a suspicious object may have been left outside the premises.
Nothing untoward was found during the search and police are treating it as a hoax.
The incident ended at 1.30am.
Sinn Fein did not respond to a request for comment.
Mr Sheehan is a former member of the Policing Board. A former hunger striker, he succeeded Gerry Adams as an MLA for West Belfast in 2010.