The government has called on Whitehall bosses to “act quickly” to bring more employees back to the office.

The letter, which the BBC saw, said it “strongly encourages” attendance through a rotation system, arguing that it would be “extremely beneficial.”

This follows criticism that too few civil servants working from home due to the coronavirus have returned to their jobs despite easing isolation.

But the unions called the government’s position outdated.

They say most civil servants should expect to continue working from home until the end of the year and that they fear an increased risk of coronavirus infection when they return with colleagues.

Analysis of mobile phone data for the last month is offered only 17% of UK workers returned to the office.

Government launched a campaign encourage people to return to work after business leaders, including the head of the Confederation of British Industry (CBI), warned that city centers can become “ghost towns”…

According to CBI’s Caroline Fairbairn, thousands of businesses that rely on passing trade suffer while offices are empty.

But Alex Brazier, chief executive of financial stability at the Bank of England, warned that the government don’t expect a “sharp return” to a “dense office environment”.

The government says it wants 80% of civil servants to be able to visit their regular workplaces at least once a week by the end of September.

And Prime Minister Boris Johnson asked officials to report on progress on a weekly basis.

In a letter sent to permanent secretaries – senior officials – of government departments, Cabinet Secretary Sir Mark Sedwill and Alex Chisholm, Chief Operating Officer of the Civil Service, say that “bringing more people back to work in a Covid-safe way will improve our government services. “.

They add: “We have seen a decline in the level of social interaction between our colleagues, with the loss of some of the spontaneous interaction and cross-fertilization between teams that stimulate innovation and support a common goal.”

But they say that the safety of personnel “remains our primary concern” and that return to the workplace will be discussed with unions and personnel groups.

The letter goes on to say: “Departments that are still below their departmental limits should now take quick steps to try to get more staff back into the office in a safe Covid manner, and take advantage of the return to schools this month and increased accessibility to public transport. … “

The FDA union, which represents senior government officials, said this week that it estimates 30% to 40% will be able to return to the office by the end of the year.

Leader Dave Penman accused ministers of being “like Luddites” in an era when technology made it easier to work from home.

And Mark Servotka, general secretary of the Union of Public and Commercial Services, said he was prepared to view strikes as “a last resort” if workers’ health and safety were “compromised.”

Meanwhile, outsourcing firm Capita – a major government contractor – plans to permanently close more than a third of its UK offices.