Local social services will be unable to cope with a growing number of dementia sufferers as the population ages, a report has warned.

Published on Tuesday by the charity Friends of the Elderly, the study calls for urgent action to prevent a "catastrophe in care provision".

Conducted by the Institute of Public Care at Oxford Brookes University, it examined services in 26 local authorities, many of whom lacked reliable information about future provision needs.

While all insisted they had a commitment to providing support, some had more developed plans for this than others, creating a "postcode lottery" in care for the elderly.

"There is going to be a dramatic increase in the number of older people with dementia in the coming years and so we are calling for a real commitment from the statutory sector to make the compact with voluntary organisations really work," said the Friends of the Elderly chief executive, Geoffrey Dennis.

"Together, with the proper planning and financial support, we can avoid a catastrophe in the care provision for older people with mental health needs."

Help the Aged supported the report's conclusions. "We need an integrated approach by government, local authorities and the voluntary sector in order to make available a comprehensive and flexible range of services to meet the needs of older people," said a spokesman.

The Department of Health highlighted an increase funding allocated to the sector.

"There have been record levels of investment in older people's services - £900 million for services to help promote independence, an extra £ billion a year by 2006 for social care services and £56 million to end long waits for NHS cataract operations," said a spokeswoman.

"We are of course aware of the projected increases in older people, and the implications in terms of future care needs.

"Local authorities and the NHS locally is best placed to assess local needs, however, our policies are designed to ensure that frail, older people receive the care that they need and want."