Every public sector employee would be given three days of extra paid leave every year to volunteer, under Conservative plans unveiled today.

Measures would also affect any employee at a business with at least 250 employees and could see around half the UK workforce becoming entitled to further time off.

Conservative Party leader David Cameron said the policy marked ‘Big Society in action’.

However Labour said the measure could ‘cost millions’ and had already ‘unravelled’ over the question of funding.

Communities secretary Eric Pickles told BBC Radio 4’s Today Programme the proposals were ‘very sensible and very modest’ with funding for organisations to cover the staff on leave ‘worked out according to patterns of work’.

‘In any large organisation you’ll want to train staff and enhance staff, and allowing staff to go out and get this new experience is going to enhance productivity,’ Pickles added.

Cameron said: ‘Today’s announcement is a double win. It’s good for our economy, as it will help create a better, more motivated workforce. And it’s good for our society too, as it will strengthen communities and the bonds between us.’

Labour’s Shadow Minister for Civil Society, Lisa Nandy, said: ‘Giving every public servant three extra days off could cost millions of pounds but there’s no sense of how it will be paid for. If just half of public sector workers took this up it would be the time equivalent of around 2,000 nurses, 800 police and almost 3,000 teachers.

‘Before the last election David Cameron made promise after promise about volunteering as part of his so-called big idea the “Big Society” - he made this same promise in 2008 when he said he wanted to give public servants time off. Since then this has become just another broken promise with volunteering falling under the Tories.’

Businesses were split on the plans, with the CBI describing its as a ‘win-win for everyone concerned’ and the Institute of Directors branding proposals ‘heavy-handed government intervention’.