Changes to safeguarding rules for people in care could cost local authorities tens of millions, council chiefs and social service directors are warning.

With a recent Supreme Court judgement meaning thousands more people could require assessment under the Deprivation of Liberty Safeguards, the Local Government Association (LGA) and the Association of Directors of Adult Social Services (ADASS) said the anticipated extra workload was likely to cost town halls at least £88m.

The set of rules is designed to ensure those who lack mental capacity are cared for in the least restrictive way possible.

In a letter to health secretary Jeremy Hunt, the LGA and ADASS warn the recent court decision could result in a ten-fold increase in additional assessments.

Both influential bodies called on the Government to fully fund the judgement to ensure councils are able to implement the changes while maintaining service quality.

LGA chair Cllr David Sparks said: ‘We completely agree with the principle of having broader, more robust checks, but the Government needs to fund councils properly so that we have the time and money to do this or there will be negative consequences on other social care services which people rely on.

‘Up until now councils have protected our most vulnerable people as far as possible and we will continue to prioritise those most in need. But it's simple – if we are struggling to afford to run the services we provide now, we will definitely not be able to afford to run additional services in the future.

ADASS president, David Pearson, added: ‘In any changes that are made, we need to make sure that the best interests of the most vulnerable in our society are identified and met.

‘This is not all about money, we also need to see urgent changes to the law which make sure that the system is clear for people to use and ensures that all people are treated the same throughout the safeguarding process, whether they are living in residential care homes, hospital settings or in the community.’