David O'Neill, president of local authorities' umbrella body Cosla, said councils across the country had deep concerns about cuts to housing benefit which, he warned, were likely to force tenants to leave communities where they have lived for years.
In a strongly worded letter, he accused Mr Mundell of misrepresenting Cosla during exchanges at Westminster, when the Scotland Office minister claimed councils' had been "satisfied" by Government assurances on implementing the cuts.
The letter, sent yesterday, has been seen by The Herald. In it Mr O'Neill says he was "taken aback" by Mr Mundell's claim, in answer to a parliamentary question from Labour MP Anne McKechin last week, that councils' and housing associations' concerns were allayed following a meeting with benefits minister Lord David Freud in November.
He said Lord Freud's assurances had been "inadequate," adding: "Considerable dissatisfaction remained, and David Freud gave an undertaking to return to Scotland to discuss the matters further in February.
"This meeting has still not been confirmed. To me it is impossible to see how this can be portrayed as Cosla and Scottish local authorities concerns having been 'satisfied'."
He has demanded that Mr Mundell "set the record straight on these matters."
He said councils had deep concerns about the plans, which from April will cut housing benefit by 14% for tenants deemed to have a spare bedroom and 25% for those with two extra rooms.
Mr O'Neill added: "At a recent meeting of Cosla, all senior councillors responsible for council housing reported being approached by anxious tenants, some in tears over what they are going to have to go through.
"Some have held tenancies for decades and seem likely to be forced to leave their communities."