A large majority of council leaders and chief executives fear their local economies will be damaged by the UK leaving the European Union.
A survey by the New Local Government Network (NLGN) thinktank also found a large majority felt they had inadequate support from government to plan for Brexit.
Economic damage from Brexit would also leave weaker local economies with less ability to raise business rates, on which local services would increasingly rely, most respondents said.
NLGN said 61% of 185 council leaders and chief executives thought Brexit would have a negative or very negative impact on their local economy, while only 12% expected a positive very positive impact, and the remainder were neutral.
Among respondents, 68% disagreed or strongly disagreed that their councils were receiving adequate support from Whitehall to plan for Brexit, with just 4% feeling this was sufficient.
Those in the south-east were the least pessimistic, while in the north east – which heavily supported Brexit in the 2016 referendum – all respondents expected economic damage, as did 93% of those in London.
NLGN director Adam Lent said: “Whatever you think of Brexit, it has to be a concern that the most senior local government figures charged with keeping their local economies buoyant feel so pessimistic.
“The government needs to move very rapidly to address this striking loss of confidence by engaging much more closely with council leaders and chief executives as they prepare for the UK’s withdrawal from the EU.”
He pointed out that housing and communities secretary Sajid Javid sits on only one of the five cabinet committees dealing with Brexit, not including the committee addressing domestic preparedness, legislation and devolution.
Mr Lent said the loss of business rates as local economies weakened after Brexit would mean “a real risk that local taxpayers will be left picking up the bill”.
NLGN said many council posts were filled by nationals of other EU member states - in particular in adult social care – and there was a risk that uncertainty around immigration rules would make them hard to recruit and retain.