Shadow Fire Minister Chris Williamson voiced concern about moves to support mutualisation of the fire service in parts of the UK.
The Fire Brigades Union has spoken out against any proposals it believes would lead to the service being privatised.
Cornwall Fire and Rescue Service and Devon and Somerset Fire and Rescue Service provide cover in the Westcountry.
Mr Williamson said: "The Fire Minister has said he wants to support mutualisation of frontline firefighting services.
"But all the while he's winking at the private sector who can see the opportunity for whopping profits at public expense.
"It's time for him to make a choice. Does he want to stick with a model of public emergency services, or is he going to betray the public trust and hand over frontline firefighting to profit-making corporates?"
But a Communities Department spokesman said: "Any attempt to characterise local plans for an employee-led mutual as privatisation are completely misleading.
"Public safety is always our first concern and we continue to work with fire and rescue authorities to ensure they provide the most efficient and effective front-line fire service there can be.
"Fire and rescue authorities will remain statutorily responsible for this public service and to suggest otherwise is completely wrong
"The Government does, however, support co-operatives and employee ownership. We are keen to work with local authorities and their staff wanting to explore the scope for employee-led mutuals where there is local support and backing."
Cleveland Fire Brigade has announced that it plans to become a "mutual" – a business owned and led by employees.
The Government says the law needs to be changed to allow the plans to go ahead, but the proposals sparked concern – appearing to go much further and open the door to a wide range of organisations taking over fire services.
Last week, Councillor Lance Kennedy, Cornwall Council portfolio holder for community safety and public protection, who effectively oversees Cornwall Fire Service, told the Western Morning News he believed there would be "no great appetite" for the proposal in the far South West.
