Volunteering England has voiced concern that changes to the welfare system could have a negative impact on volunteering.
In a briefing document on universal credit, the organisation warns that the new single payment for jobseekers and low-income earners – which comes into force next year – will restrict the amount of time people on benefits can volunteer.
Dan Sumners, senior policy and communications officer at Volunteering England, said the membership body had already received calls from charities worried about the new regulations.
Under universal credit, claimants will be expected to spend up to 35 hours a week looking for or preparing for work. But the new rules state that volunteering by people in receipt of the payment will be restricted to "up to 50 per cent of their expected hours of work search". Currently, there are no specified restrictions.
The document prepared by Volunteering England on universal credit said: "There is likely to be some concern, among volunteers and the organisations that involve them, that the introduction of a mandatory level of work search also introduces a regulatory restriction on volunteering."
A spokeswoman for the Department for Work and Pensions said: "We recognise the value of volunteering and the contribution it can make towards helping a claimant into work.
"Under universal credit, people looking for work will be able to spend half their jobseeking time volunteering – but it’s only right that claimants do all they can to move into work or take up more or better-paid work."