Companies should reduce employees' hours to 20 a week, so they can take on twice the number of staff and solve the unemployment crisis. That's the suggestion being made by the New Economics Foundation (NEF), a think-tank.

The proposal will be put forward at a meeting at the London School of Economics this Wednesday organised by NEF.

The NEF claims: "A ‘normal’ working week of 21 hours could help to address a range of urgent, interlinked problems: overwork, unemployment, over-consumption, high carbon emissions, low well-being, entrenched inequalities, and the lack of time to live sustainably, to care for each other, and simply to enjoy life."

The NEF's proposal, which it says would have the useful bonus of helping to reduce carbon emissions, comes as a recent study by the Trades Union Congress suggests many Britons are doing unpaid overtime - adding up to 2 billion hours for the whole country every year.

However the proposal has been criticised, with some arguing that attempts to do the same thing in other countries hasn't worked.

Dr Wilson Wong, senior researcher from the Work Foundation, described the proposal as a "mechanical formulation" which couldn't work in practice.

"It's not always clear that the issue is that there is too much work for too few workers," he told HuffPost UK. "What's driving the long hours can also be a need for job security and the financial obligations that rest on people.

"The French tried this when they lowered the number of hours in their working week and I'm not entirely convinced they addressed the problems."

Dr Wong suggested that in fact companies were moving in the opposite direction, asking people to work longer hours to fill gaps.

"When a short-term vacancy arises, such as maternity cover, firms often use this as an opportunity to test out new employees in a new role, in addition to their current job. Although it means a longer working week, it gives organisations a better opportunity to assess people in a different light and helps people further their career goals.

"We're not advocating that people should be working longer hours, but treating this as a problem which can be legislated away, I don't think it's do-able. There are just so many permutations."