Prime Minister Scott Morrison has revealed a new social distancing measure as all non-Australian citizens or residents are banned from entering the country.

The announcements come after a meeting of the national cabinet and state leaders.

The federal government is requesting those in offices, restaurants or other spaces ensure there is four square metres per person.

In practical terms, this means a room of 100 square metres should only have 25 people in it.

“We are now moving to an arrangement for gatherings of less than 100 and that there would be four square metres provided per person in an enclosed space, in a room,” he said

“So that’s two metres by two metres.

“So, for example, if you’ve got a room, if you’ve got a premises, if you’ve got a meeting room or something like that, that’s 100 square metres, then you can have 25 people in that room,” Mr Morrison said.

• Related: Sydney woman is Australia’s seventh coronavirus death
• Related: NAPLAN tests scrapped for 2020
• Related: Banks offer six-month home, small business loan holidays
• Related: Normal rules no longer apply, warns UN chief

Schools, universities, airports, public transport, medical and emergency services facilities, aged care homes, jails, courts, parliaments, supermarkets and many workplaces are exempt from the indoor gathering restrictions.

Chief Medical Officer Brendan Murphy reiterated the advice, saying the situation was “critical”.

“We have to slow the curve … there is a risk if we don’t do what everyone of us has to do as our civic duty to control this spread it will grow significantly greater,” Dr Murphy said.

This advice comes with its own implications for Parliament.

Government and opposition whips will minimise the number of members and senators from remote areas or who have the longest travel requirements.

If a Parliamentarian is sick or self-isolating or consideration needs to be given to the welfare of their communities, pairs will be made.

During question time at 2pm, only the required ministers, members and senators attend the chambers to reduce the number of members and senators in each chamber.

Some variations will be made to procedure to enable members and senators to observe “social distancing”.

For example, ordinarily they must be in their own seat to speak, but the rules will be bent to allow speaking from another seat.

Members and senators can only bring a limited number of staff, while the public gallery will be closed and visitors to Parliament House limited.

Restrictions on movement are set to be extended, with all non-Australian citizens or residents banned from entering the country from 9pm AEDT Friday. Direct family members will still be permitted.

National cabinet will consider on Tuesday further travel restrictions which will apply in the Easter school holidays.

But people planning holidays should “reconsider any unnecessary travel”.

Concern has been expressed about Indigenous communities, deemed more susceptible to the virus’ effects.

States and territories will nominate specific areas which will be subject to entry restrictions, to help minimise the spread into vulnerable communities.

Some travel exemptions will apply, including for medical treatment, food and medical supplies, mental health and domestic violence support and emergency services.

Similarly, all workers in the aged-care sector will be test and all health care workers exhibiting cold-like symptoms will be tested.

-with AAP