Public spending cuts are likely to hit volunteering hard, a charity chief has warned.
Dame Elisabeth Hoodless, the outgoing head of the Community Service Volunteers (CSV) organisation, used an article in the Times to flag up her concerns as she stepped down.
Downing Street responded by saying councils needed to do more to find efficiency savings before making sweeping cuts to external organisations.
"We know we need to save money, but there are other ways of saving money without destroying the volunteer army," she wrote.
David Cameron's 'Big Society' initiative is a key part of the coalition government's agenda. It emphasises greater involvement in public issues by private firms, local communities and - critically - the volunteer sector.
Dame Elisabeth, who was originally a strong advocate for the Big Society said the coalition's austerity drive was undermining the idea, however, by forcing cuts to volunteer activities already in existence.
"It's about one hand not appreciating what the other hand's doing, and not getting the decisions made in a timely fashion," she told the Today programme.
"There are a lot of people putting a lot of energy into the Big Society, but it's not strategically planned."
She said volunteers working in child protection promoted by the schools minister were now under threat of closure because of local authority cuts.
"Similarly the government's programme to spend six weeks meeting people from different backgrounds in the summertime... [is being funded] by withdrawing funding from a multiplicity of initiatives across the nation involving volunteers," Dame Elisabeth added.
No 10 said the government had to look at local government spending because it represented a quarter of all public money.
"Local government can make efficiencies and they shouldn't be going immediately to external organisations and saying 'we're going to cut this'," the prime minister's spokesperson said.
The coalition wants local authorities to look at pay accommodation and buildings in particular in order to save money.
"We want to see a greater role for voluntary organisations in... rehabilitating prisoners, for example," the prime minister's spokesperson added.
"They will become service providers and fulfilling contracts... but that is clearly going to take more time."
Dame Elisabeth called on the government to set targets for public organisations linking funding with volunteer numbers, as takes place in some parts of the US.
"The question about involving volunteers should be an early question, not a late question," she added.
The development follows a decision by Liverpool City Council to pull out of the Big Society initiative.
The move was a particularly damaging one for the Conservatives, who had pointed to the Labour-run council's support for the agenda as proof that the Big Society could work across party lines.
But in a two-page letter, city council leader Joe Anderson said public spending cuts had seriously undermined the ability of community groups to improve quality of life.