Events, tours and banquets in the Houses of Parliament have been shut down for two weeks because of a Covid outbreak on the estate.
MPs hoping to host talks and gatherings have been told they must cancel due to a “major incident”.
An email sent to staff, seen by HuffPost UK, said: “All events on the estate that do not relate to parliamentary business will be cancelled for the next two weeks, including banqueting events (member-sponsored and third party), tours and other meetings.”
Authorities declined to comment on the current scale of cases on the parliamentary estate, but there has been an increase among MPs, ministers and staff.
Their email said the “recent increases” in Covid-19 across the country were being “reflected in parliament” and the UK Health Security Agency had determined the risk of transmission on the estate was “now greater”.
It was also reiterated to staff they “should” wear face coverings on the estate unless they have a “legitimate exemption”.
They were told masks should “only” be removed when seated at their desk, during meetings if required to speak, or when eating or drinking.
Workers have also been told to “maintain distancing” as much as possible on the estate.
Meanwhile, all face-to-face meetings between colleagues “should be avoided” unless there is a “business need”.
“Colleagues must space out and avoid sitting directly opposite each other in working areas. Avoid close contact at all times,” the memo added.
MPs’ staffers have been seen getting a telling off from authorities on the estate for not wearing masks.
Some, who are sceptical of the measures, raised concerns that they will set a precedent for the rest of the country.
Others are annoyed that they have to wear masks at work while MPs - who are not employed by the Commons authorities - cannot be forced to wear them.
Leader of the Commons Jacob Rees-Mogg recently claimed that Conservative MPs do not need to wear masks because they all know each other and share a “convivial and fraternal spirit”.
Jawad Raza, from the FDA union for senior civil servants, told HuffPost UK it was time MPs drop the “political pandering” and follow the same rules as everybody else.
He said it was “welcome” that the house was “finally” putting additional measures in to control the rising numbers of cases on the parliamentary estate.
But, he added: “It is imperative that all MPs wear masks to protect each other and parliamentary staff – and not just for keeping up appearances on television.
“This is a serious issue of health and safety and it’s high time MPs stop making light of the matter and show some leadership and responsibility.
“Our message to MPs is simple: drop the political pandering and set an example by following the same rules as everybody else.”
HuffPost UK has also seen a list of so-called “trigger points” parliament is using to dictate when measures are brought in.
However, the authorities said they would not provide a running commentary on specific numbers of cases.
After the news broke, Conservative MP Karl McCartney suggested reports had appeared in the media before MPs were briefed – something the speaker has criticised the government for.
Sir Lindsay Hoyle replied: “I’m very pleased in the way you’ve approached the question to me – a bit better than your email earlier today, which was pretty offensive so I think we ought to think about how we address each other in emails.”
Hoyle then cut off a point of order from another Tory MP William Wragg on the issue, adding: “I’m not going to go into further debate” and “I’m certainly not going to be tested today”.
A parliamentary spokesperson said it was their “priority” to ensure those on the estate are “safe” while business is facilitated.
They cited rising cases, adding: “As a consequence, some further action is being taken to ensure that case numbers do not continue to rise. The measures will be reviewed in two weeks’ time.”