Cuts to BBC local radio could jeopardise emergency broadcasts during civil crises, councils claimed today.
The corporation wants to axe medium wave output in parts of the country where alternative FM services are available.
But the Local Government Association (LGA) said the plans would threaten advice messages during floods, heavy snowfall and major traffic accidents.
The LGA, which represents more than 350 local authorities in Wales and England, said the FM frequency often broadcast "cracking static" rather than clear sound.
Its culture board chairman Chris White said: "Local radio plays a key role in how councils manage an emergency and the BBC regularly sits on resilience planning panels along with police and fire authorities.
"Time and time again these arrangements have proven invaluable to local communities, from updates about school closures, heavy snowfall, road accidents and flooding, to bulletins about more unforeseen emergencies such as train crashes or dangerous criminals on the loose.
"People rely on councils for the latest information in many circumstances, and in turn we rely on local radio."
He feared the BBC was "underestimating the serious implications and risks to people's safety" and called on it to remember its public service duty.
He added: "Its proposed contingencies barely sound adequate on paper and in the reality of an emergency could well be found wanting.
"Residents may end up with confused broadcasts from inexperienced journalists reporting on places they know nothing about, while others with no medium wave service could be left entirely in the dark. Both are unacceptable."
A BBC spokeswoman said: "BBC Local Radio will continue to be local in times of crisis or emergency, that will not change.
"The proposal is to end medium wave transmissions, except for stations where listeners depend on medium wave as an alternative to FM.
"We will consider carefully submissions from those areas that can show they would be disadvantaged by the withdrawal of medium wave.
"The BBC Trust is consulting on these proposals and no decision has as yet been made."