New measures will be brought in throughout Parliament to protect MPs and staff from coronavirus.
Commons Speaker Sir Lindsay Hoyle has written to members with a list of changes “to protect our parliamentary village” and “keep… the House going”.
The measures include installing Perspex screens in the Commons and advising further use of face coverings.
It comes after MP Margaret Ferrier travelled to and from Westminster despite experiencing Covid symptoms.
The Speaker said on Friday he was “very, very angry with the MP, for putting MPs and staff at risk.
She has been expelled by the SNP but has not stood down from Parliament.
In his letter, Sir Lindsay confirmed there had been “a small number of cases on the Parliamentary estate”.
Both the Commons and the Lords are still running a “hybrid Parliament” where members can join in debates via video link and vote using proxies.
But a limited number are allowed in the chamber and many members have returned to Westminster.
The BBC understands MPs in favour of looser restrictions asked the Speaker some weeks ago for 16 more members to be allowed in to the Chamber during debates – but were told they would have to wear masks and sit behind glass screens.
Sir Lindsay wrote: “As your safety and wellbeing is our top priority, I called a special meeting of the House of Commons Commission [on Tuesday] to discuss ways to protect our parliamentary village, while keeping the business of the House going.
“The Commission is trying to keep the House functioning in the safest way possible, within the remit of its responsibilities and following guidance from Public Health England.”
The most visible change will be the addition of Perspex screens at the end of the green benches nearest to the Speaker’s chair, as well as at the end of the clerks’ table and to one side of the Serjeant at Arms’ chair.
The authorities are also considering creating a new voting lobby to split the queues of voting members.
MPs are being “strongly advised” to wear face coverings when moving around the site – especially when going from one building to another or queuing for food – but they do not have to wear them in the Chamber or their offices.
Members were also told off for not always maintaining a social distance.
“It’s for everyone’s safety,” wrote Sir Lindsay. “So please keep your distance and I would ask you to co-operate with staff who have been asked to remind colleagues of the rules.”
Finally, the Speaker reiterated his plea for any member of Parliament or staff to stay away from work if they are experiencing symptoms or to return home if they feel unwell or get a positive result – pointing to London accommodation first, before heading elsewhere in the country.
He concluded: “I would encourage you all to take personal responsibility for keeping yourself and your staff safe.”