There have been reports in the media about delays to passport applications following the Corona outbreak and the lifting of some travel restrictions.
Due to small and often cramped offices, social distancing is difficult to observe and HMPO is struggling to get its 4,000 staff members back into the workplace
People applying for passports are experiencing lengthy delays, with some having to wait as long as 143 days.
Ministers lifted the ban on non-essential travel to 70 popular destinations earlier this month, in a bid to stimulate travel abroad and to attempt to revitalise the sector.
However PCS has been clear that its five tests must be met before there can be a safe return to work, when Covid-19 is still widespread and the 'R' is close to 1.
PCS general secretary Mark Serwotka said: “Where Covid-19 is still not under control, it would be unsafe for our members to return to work.
"Staff who are at work are flat out trying to ensure that passports are processed as quickly as possible.
“However the safety of our members is our primary concern.
"We are demanding proper health and safety risk assessments are carried out before members should return to the workplace.
"The union has also suggested mandatory temperature checks for staff returning to work but HMPO have refused.
"Passport offices are often small and we cannot guarantee our members will be able to adhere to social distancing.
“We have reports that the HMPO is looking to keep offices open till 10pm to allow a skeleton staff to fulfil their hours.
“HMPO has already shown it sees members safety as secondary to getting routine work done and this is not acceptable.”