A government department has been accused of having a "seriously flawed" understanding of the pressures felt by fire and rescue services amid cuts in funding.
The charge was made by MP Meg Hillier, who chairs the Public Accounts Committee, following publication of a report warning of the effects of further cuts.
The National Audit Office (NAO) warned of risks to the safety of firefighters and the shrinking of the fire service.
It found that funding for fire and rescue authorities had fallen "significantly" in the last five years, but fires and fatalities both continued to decline over the same period.
The number of firefighters has been cut by 14% in recent years, while fewer audits of business premises have been carried out and less hours are spent on home fire safety checks.
Authorities sometimes send fewer firemen and women to incidents, and some are warning that their capacity to respond to major incidents might be compromised by further funding cuts, said the NAO.
"Given the savings made to date, a number of authorities anticipate that further savings will only be possible via further reductions in firefighters, and have expressed concerns at the potential impacts this may have," said the NAO.
Ms Hillier said: "The Department for Communities and Local Government's understanding of the pressures now faced by fire and rescue services is seriously flawed. Without this understanding, further efficiency savings could put services at risk, potentially putting lives at risk.
"Fire and rescue authorities have faced significant financial challenges over the last five years. Despite funding cuts of up to 38% since 2010, they have worked hard to continue to deliver the same standards of service and reduce the number of fires and casualties.
"But maintaining services has come at a cost. The number of full-time firefighters has fallen 14% since 2010-11. Finding year-on-year savings while protecting firefighter levels will be increasingly difficult and some authorities already report that their capacity to respond to major events will be put at risk by further reductions."
Amyas Morse, head of the National Audit Office, said: "Fire and rescue authorities have managed funding reductions well since 2010. There have been no financial failures and the numbers of fires and casualties have continued to fall.
"I would expect the Department for Communities and Local Government to have a better understanding of the appropriate funding level necessary to support services, in order to maintain the financial sustainability of the sector in the context of funding cuts. The Department should also seek greater assurance that authorities are maintaining service standards and delivering value for money locally."
Matt Wrack, general secretary of the Fire Brigades Union, said: "This report confirms what we have been saying for years. Cuts in funding are leading to slower 999 response times. This means beyond doubt that people will be injured or even killed needlessly, and property lost that need not have been.
"To ignore these facts by offsetting these losses against fewer fires is a cynical attempt to gloss over the facts.
"This government is failing to provide public oversight of the fire and rescue service, with no proper system of scrutiny. Local services set their own standards and then change them when they don't meet them. All the claims about local accountability are therefore utterly meaningless.
"There needs to be a system of independent inspection so that government has real assurance as to whether we can deal adequately with national risks such as terrorism, major floods or other major incidents.
"This government has overseen the fragmentation of what was once one of the finest fire services in the world. We cannot sit by and watch as it is dismantled."
A Department for Communities and Local Government spokesman said: "We are disappointed that the National Audit Office's report does not recognise the excellent work of fire and rescue authorities in reducing fire deaths and incidents by around half over the last decade.
"We collect and publish an extensive range of data from fire and rescue authorities across the country on spending, performance and outcomes, which show improvements across the board.
"DCLG has considerable expertise in this area which allows us to challenge and validate the data and we are confident that services have been maintained while making valuable savings for taxpayers."