The UK Government has asked local authorities in England to house all rough sleepers by the weekend, the charity Crisis said.
An email sent to homelessness managers and rough sleeping co-ordinators in every local authority, is quoted by the charity as saying: "As you know, this is a public health emergency.
"We are all redoubling our efforts to do what we possibly can at this stage to ensure that everybody is inside and safe by this weekend, and we stand with you in this.
The charity said the email was sent by the Ministry of Housing, Communities and Local Government.
Crisis chief executive Jon Sparkes said: "The Government's insistence that everyone sleeping rough should be housed by the weekend is a landmark moment - and the right thing to do.
"Questions remain about how local councils will be supported to do this, and whether additional funding, or assistance securing hotel rooms, will be made available.
"We also need to see a package of support so that, when the outbreak subsides, the outcome is not that people return to the streets.
"The Government has committed to ending rough sleeping by 2025 - this proves it can be done in 2020 if we make it the priority it deserves to be."
To get "everyone in" by the weekend, Crisis says the Government should launch a national appeal for accommodation, which would include empty apartment blocks and hotels.
The Health and Social Care Committee of MPs, which met on Thursday, heard concerns that some hotels were resistant to making rooms available for homeless people.
Conservative MP for Watford, Dean Russell, said his impression was that hotels are open to helping NHS workers and people in care but "fear there might be damage to rooms or related issues" if they help the homeless.
A Ministry spokesman said: "We are working intensively with councils and the sector to get everyone who is sleeping rough off the streets and into appropriate accommodation - backed by APS1.6 billion of additional funding for councils to respond to pressures during this national emergency.
Australian Associated Press