The Prime Minister said people were returning in "huge numbers to the office" – but Downing Street said it could not yet provide information to back up the claim.
It comes as the Government is pushing for the civil service to lead from the front by returning to their desks, with a PR blitz due to commence this week encouraging all employees back to their workplace.
The next phase of the Government's All In, All Together campaign will remind workers about the efforts taken to make workplaces "Covid-secure", Downing Street said.
Boris Johnson, addressing his Cabinet members as MPs prepared to return to Parliament after the summer recess on Tuesday, said: "People are going back to the office in huge numbers across our country, and quite right too."
The Prime Minister's official spokesman told reporters that the public could expect to see civil servants curtailing their work-from-home habits.
But Number 10 said it was too early to be able to share data detailing how many people nationally had gone back to work, including how many in Whitehall were back to their work stations.
Mr Johnson's spokesman said: "I don't have the figures especially for today but you can expect to see more civil servants return to the office over the coming weeks with the return of Parliament and children to schools.
"We've been clear with departments that they need to ensure Government work spaces are Covid-secure and permanent secretaries have been undertaking the work to return civil servants to the office or workplace."
Downing Street fears huge job losses in town and city centre shops and cafes if workers do not return to their pre-lockdown commuter patterns.
Nickie Aiken, Tory MP for Cities of London and Westminster, told BBC Radio 4's Today programme that as many as 50,000 people in the capital's retail sector faced losing their jobs due to the lack of visitors, and pinned part of the blame on a "huge fall-off in confidence" regarding the perceived safety of public transport.
The Prime Minister's spokesman said: "The message from the PM is he recognises the importance that returning to work has in stimulating the economy, and that's why we have changed the guidance to give employers more discretion in how employees can work safely."
The comment comes after Health Secretary Matt Hancock said last week he had "absolutely no idea" how many Department of Health civil servants had returned to the office and added he cared more that they were doing their jobs effectively.
Asked by reporters whether the Prime Minister agreed with his Cabinet colleague's relaxed position, Mr Johnson's spokesman said: "We've been clear we want departments to make their work spaces Covid-secure and they will of course take employees' individual circumstances into account, with no individual having to return if there are health reasons for them not doing so.
"But we want to see more civil servants back in the office."
The spokesman added that the All In, All Together campaign would be "reiterating our guidance on how to return safely to work" when it kicks back into gear this week.
But devolved leaders, opposition MPs and union chiefs were critical of the campaign's new messaging when it was briefed last week.
Scotland's First Minister Nicola Sturgeon said she would not "intimidate people back to work".
Meanwhile, Number 10 confirmed Boris Johnson has joined social and business networking website LinkedIn.
"The purpose of that is it is another platform for him to engage directly with businesses and workers, and that's something that's particularly important during the economic recovery from the coronavirus pandemic," said his spokesman."