In Scotland, 362 firefighters and control staff are currently in isolation – around five per cent of the work force – although other UK fire services report up to 12 per cent.
In total there are 3,000 staff currently in self isolation and unable to work.
The Fire Brigades Union says emergency services will be hampered in their performance unless personnel are urgently given tests.
Control rooms answering 999 calls cover huge numbers of people from a single room and the union believes just one person developing coronavirus could seriously impact this service for an entire region.
Some firefighters are driving ambulances and assisting paramedics, delivering food and medicine or helping police remove dead bodies.
A recent agreement with the UK Government also means firefighters can fit masks and respirators for NHS workers and deliver protective equipment to health trusts.
Matt Wrack, FBU general secretary, said: “The Westminster government is playing with fire by not testing firefighters and control room staff for coronavirus. Currently, crews are maintaining services, but this will become increasingly difficult as the virus spreads.
“There are already thousands of firefighters and control staff in self-isolation, only a fraction of which will have the disease. If we aren’t able to find out exactly who is infected, and more staff isolate unnecessarily, services will be put on a dangerous knife-edge.
“Of course, testing of NHS staff has to be a priority, but firefighters and other emergency service personnel are also at serious risk. The very safety of the public relies on them being able to attend work. There needs to be a clear and deliverable testing strategy for all workers required to continue at work.
“The government failed to secure test kits in sufficient numbers early in the pandemic and now frontline services are paying the price. Devolved governments have begun to take steps in the right direction, but in Westminster time is standing still – ministers need to get to grips with this crisis and ensure that all emergency service personnel are tested as soon as possible.”
Ross Haggart, Deputy Chief Officer of the Scottish Fire and Rescue Service, said: “As part of our preparations for the coronavirus (Covid-19) outbreak, we have taken steps to equip all staff with the appropriate knowledge to protect themselves and prevent spread of infection in line with the guidance issued by NHS Scotland and the Scottish Government.
“At present, we are maintaining high resilience across our service. We also have robust contingency plans in place should we encounter a high number of absences to ensure we continue to respond to every emergency, and continue to review this regularly.”