One of the bars in Parliament will close on Monday for a security and safety review after a report that a woman had her drink spiked.

The alleged incident occurred in early January at the Strangers’ Bar, which is open to MPs and their guests as well as parliamentary staff.

“The safety of everyone on the estate remains a key priority of both Houses,” a House of Commons spokesperson said.

The bar, which is not usually open on Fridays or over the weekend, will be shuttered while security and safety arrangements are reviewed. Police are also investigating.

A parliamentary researcher reported her drink had been tampered with to bar staff and security on Tuesday 7 January, the second day of Parliament after the festive break.

The branch of the GMB union that represents MPs’ staff said the closure was “very encouraging”.

“The House authorities have a duty of care for the whole parliamentary community, but this is especially important for MPs’ staff, given the vulnerabilities we face with power dynamics,” GMB branch chairwoman Jenny Symmons said.

“The GMB will be following this review and the outcomes closely.”

A Met Police spokesperson earlier confirmed an investigation was under way and the victim was being supported.

Prime Minister Sir Keir Starmer found the reported spiking “incredibly concerning”, No 10 said.

Home Secretary Yvette Cooper earlier condemned spiking as “a disturbing and serious crime which can have a damaging and long-lasting impact on victims”. The government has also pledged a crackdown on violence against women and girls through the Crime and Policing Bill.

Parliament’s official complaints authority, the Independent Complaints and Grievance Scheme (ICGS) has criticised Westminster’s heavy drinking culture as a “frequent factor” in complaints and breaches of the code of conduct.

The watchdog found drinking in Parliament’s many bars often led to “intimidating behaviour” based on 30 ICGS investigations between 2021 and 2022 announced in October.