text: David Cameron today announced plans to give millions of workers three days paid leave a year to do volunteer work. The Prime Minister said he will amend the Working Times regulations so for three days people can volunteer or serve as a school governor, and get paid in addition to their 28 days of paid holiday. But business leaders criticised the move as heavy-handed government intervention', amid doubts about how the policy would be paid for. Scroll down for video . Happy handshake: The Prime Minister met staff and volunteers at the Age UK Day Centre in Plymouth today . Prime Minister David Cameron's Big Society good deeds scheme will only affect firms with 250 or more staff . The policy will apply to workers at firms with at least 250 staff - an estimated 10 million in the private sector and five million in the public sector. Volunteers would be able to take the time to volunteer in a block or flexibly. Announcing the policy Mr Cameron said: 'This election is about building a better future for our children and grandchildren. The foundation stone of that better future is our economic security. But Conservatives know the society we build on top of that is just as important too. 'This is the clearest demonstration of the Big Society in action - and I'm proud it's a Conservative government that will deliver it.' But Simon Walker, director general of the Institute of Directors (IoD), criticised the announcement, saying the policy did not appear to have been thought through. 'Many, many businesses are already highly engaged in their local community and with charitable causes, and the IoD thoroughly supports them. Passing a law to compel firms to pay their staff to volunteer for charity is hardly in keeping with the spirit of philanthropy. 'Businesses should support their staff if they want to volunteer, but the architects of this idea cannot pretend that forcing firms to give an additional three days of paid leave will do anything other than add costs. Time off for charity work and volunteering is a matter for managers and employees to discuss between themselves, not a target for heavy-handed government intervention. 'This announcement not only undermines the Tory record on reducing business regulation, it also puts additional pressure on public sector employers, and ultimately the taxpayer. Frankly, the essence of volunteering is that it is voluntary. The IoD would welcome proposals to incentivise and make it easier for companies to facilitate volunteering, but it has to be a choice.' Mr Cameron's plan will affect around 15 million workers across Great Britain in private and public sectors . Survival expert and Television star Bear Grylls said that he supports Mr Cameron's volunteering scheme . The plan was praised by the chairman of BT Mike Rake. He said: 'Corporate volunteering is a triple win - a win for the community, a win for individuals doing the volunteering, and a win for companies.' Survival expert and TV star Bear Grylls also lent Mr Cameron his support for the scheme. 'Any initiative that encourages people to volunteer is good news,' he said. 'All of us struggle to find extra time and that's why to have firm government support that enables millions to volunteer is a huge step forward towards building solid communities all around the UK.' However, just hours after Cameron's announcement, Communities Secretary Eric Pickles said companies would not be forced to organise paid time-off for their employees, suggesting the policy would be unworkable. 'Nobody is forcing anybody to volunteer and no one is forcing companies to organise this volunteering if it causes problems to the company,' Mr Pickles told BBC Radio 4's Today programme. He added there would need to be 'a bit of give and take' with the Prime Minister's plan. The Communities Secretary insisted it would not add to costs in the NHS, with potential gaps having to be filled by extra agency workers. 'We're talking about three days and it would be worked out according to patterns of work and it will be worked out to ensure that it doesn't cause inconvenience to the health service,' he said. The former Deputy Prime Minister John Prescott said Mr Pickles had given a 'car crash' interview. He tweeted: 'If yesterday's Michael Fallon interview was a car crash, Eric Pickles just caused a motorway pile-up #r4today.' Mr Pickles suggested companies would not be forced to give staff days-off for volunteering under the plan . Former Deputy Prime Minister John Prescott offered his view on Pickles' interview on the Today programme . The Labour party raised concerns about the cost of the policy. Shadow minister Lisa Nandy said: 'This is a re-announcement from David Cameron that has unravelled before it's even been made. '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.'
target: Prime Minister announced plan to amend Working Times regulations .
  Mr Cameron wants workers to have three paid days off to do good deeds .
  He described announcement as  demonstration of the Big Society in action .
  Immediately afterwards Eric Pickles suggested it wouldn't be enforced .
  John Prescott described Mr Pickles' interview as a 'car-crash'