Volunteer groups could be the biggest victim of Government spending cuts which would "ravage communities", the sector's umbrella body has said.
The National Council for Voluntary Organisations (NCVO) published a report into recent trends in Government funding.
It said that vital services could disappear if volunteer groups fell prey to future funding cutbacks.
Currently the Government gives £12 billion to the sector per year and around 25,000 groups depend on the cash for three-quarters of their income.
As this accounts for only 2% of Government spending on public services, the NCVO fears it could be seen as an easy target for cuts.
A spokesman said: "It only accounts for 2% of expenditure and a lot of contracts are coming up in 2010 and 2011 which will have to be renewed. Any potential new Government that comes in will look to make some cuts. They might look at it and say 'it's only 2%, we can get rid of it' but it would make a dramatic difference to the services offered by voluntary organisations.
"Sometimes they are the only organisations that can get to hard-to-reach people."
The groups deal in areas which include health and social services, training, law, education and housing.
Chief Executive of the NCVO, Stuart Etherington, said: "Public sector funders must avoid a knee jerk reaction. Ill thought out cuts would ravage communities across the UK.
