Millions of British employees failed to take billions of days in holiday entitlement this year, research has revealed.

One in three workers will not have taken their full holiday entitlement, wasting a staggering 14.5 billion of holidays. The failure to take time off means thousands of British companies could be inadvertently flouting national Working Time regulations.

These came into force in 1998 and stipulate that all workers should have a minimum of four weeks paid leave.

The widespread practice of leaving holiday entitlement unclaimed is also a substantial hidden drag on British business efficiency.

Staff who fail to take time off are more likely to suffer stress and other health problems, which can have a knock on negative effect for

employers. The research into UK 'holiday debt' was carried out by Croner/YouGov which polled 536 people whose holiday entitlement runs from January to December.

With only a few working days left in 2005 researchers discovered only one in five people have claimed their full holiday allowance.

A full 26 per cent still have seven or more days left to claim, while a further 26 per cent have four to six days remaining.

Of the 33 per cent who won't be claiming full holiday entitlement seven per cent, equal to 2.2 million of the total working population, will lose their holidays altogether.

Of the rest, 21 per cent expect to carry over their entitlement to 2006 with four per cent opting for payment instead.