Until recently much of the £28m given to organisations in the voluntary sector annually has been ring-fenced and distributed by the London Councils’ Grants Committee.
But unions say changes to funding in London will mean the money is now given to local councils with no guarantee it will be spent on voluntary groups.
The NHS Confederation has warned that the cuts to council funding and social care budgets will increase the demand for health services.
Doug Nicholls, Unite officer for the not for profit sector, said the changes would worsen 'some of the capital's most entrenched social problems.'