Staff working for Her Majesty's Passport Office believe their lives are being put at risk because of demands that they return to work.
Many have been asked to go back next week, despite the ongoing coronavirus crisis, the BBC has learned.
On Tuesday, staff were told by a Home Office scientific adviser 80% of people would get Covid-19 in the end and "we can't hide away from it forever".
The Home Office said it was maintaining social distancing at passport offices.
When and how to get staff back into the workplace are questions employers will increasingly have to grapple with across the UK.
Her Majesty's Passport Office (HMPO) has centres in Belfast, Durham, Glasgow, Liverpool, London, Newport and Peterborough.
The Tuesday conference call was addressed by Myrtle Lloyd, the HMPO chief operating officer.
According to a transcript seen by the BBC, she said government health guidance did not mean that staff "should stay at home instead of delivering critical services".
"What is also critical for us as a business is to have a manageable level of work in the system, so that when we start our recovery we are not overwhelmed by our demands," she said.
Sources at the Public and Commercial Services Union said up to 2,000 staff would be asked to go back in, with 500 in offices at any one time.
However, dozens of staff sent messages that they were deeply concerned about returning to work.
One wrote: "Your actions are going to kill people."
Another said: "If my family die because you insist I need to come to work before the surge passes (having isolated until now), I will pursue a claim against HMPO / Home Office for negligence."
Others questioned how they would get to work without using public transport.
There are also claims among staff and their trade union that advice from a government official at the meeting was out of step with government policy.
According to the transcript, the Home Office deputy scientific adviser, Rupert Shute, told those listening that staying at home was important but "we also have to keep functioning our lives".
"You are no more at risk at the workplace as you would be in your home or at the supermarket. It is about minimising it," he said.
"We are working on the assessment that 80% of us, if we haven't already, will get the virus."
He added: "We cannot hide away from it forever."
This echoed previous government briefings that up to 80% of people would eventually contract Covid-19 and that this would help the population develop "herd immunity".
However, that position was sidelined when computer modelling suggested a lockdown would be needed to reduce the infection rate.
The Public and Commercial Services Union said his comments were "extremely irresponsible and totally contradicted current government guidance".
PCS general secretary Mark Serwotka said: "It is absolutely scandalous that HMPO are suggesting our members can go back into work during a pandemic to process routine passports.
"The cavalier approach to our members' health and safety is shameful and ultimately puts them in greater danger of contracting Covid-19.
"We have already had members die as a result of contracting coronavirus and pressured Civil Service managers in other departments to shut offices so staff can work from home."
A Home Office spokesperson dismissed suggestions the health of staff was being put at risk.
In a statement they said: "Her Majesty's Passport Office is fully adhering to public health advice across all of its offices and adopting social distancing measures to keep both its staff and customers safe.
"It continues to operate at substantially restricted staffing levels with a significant number of people working from home where possible, and staff are prioritising emergency cases.
"Guidance is also available for people who are travelling into work.
"It was made clear in the meeting that the government's priority is slowing the spread of coronavirus and we all have a part to play in order to protect the NHS and save lives."
Passport Office staff have to handle documents and passports sent in from all over the world.
One source said they and their colleagues were happy for a skeleton staff to process applications needed for ID purposes, especially when the applicants were doctors or nurses.
However, they are now dealing with requests for passports before holidays over Easter, but the shutdown of most air travel meant they were no longer urgent, the source said.
A key computer system they use cannot be installed on laptops and security measures make it difficult for operation staff to work from home.
The Passport Office is looking for new ways to help them to do so.
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