UK employers paying the voluntary "real living wage" are being asked to raise salaries by almost 7 per cent for the coming year to reflect sharp increases in the costs of essentials and changing expectations of living standards.

The Living Wage Foundation, a charity that campaigns on pay and working conditions, said on Wednesday it was increasing its national living wage rate by 6.7 per cent, from £12.60 to £13.45 an hour, with a 6.9 per cent increase in its London rate from £13.85 to £14.80.

The change will directly benefit about half a million people working for 16,000 employers who are accredited by the charity, ranging from Premier League football clubs to retailers such as Lush and Ikea. But it could benefit many more indirectly as some large companies, including supermarkets, use the rate as a benchmark to set entry level pay and unions often use it as a reference point in collective bargaining.

It will also widen the gap between workers receiving the "real living wage" and those paid the UK's statutory minimum. Official data due later this week will underpin next year's increase in the statutory "national living wage", the legal minimum hourly rate for workers aged 21 and over across the UK. This is expected to rise by about 4.1 per cent to £12.71 next April in order to keep it steady at two-thirds of UK median earnings.

The Foundation said a full-time worker on its new rates would earn £2,418 more per year in the UK than the current minimum wage and £5,050 more in London. "We encourage as many employers as possible to do the right thing" and adopt the rates, said Katherine Chapman, the charity's executive director.

The number of accredited living wage employers had continued rising over the past year, the Foundation said, but it acknowledged that growth had slowed as businesses fret over a rise in labour costs exacerbated by last April's increase in employer National Insurance contributions.

Employers in low wage sectors such as retail and hospitality say the combination of higher taxes and legal minimum wage rates has forced them to cut headcount over the past year.

Think-tanks are warning the government to be cautious about raising the statutory minimum wage too rapidly this year -- in particular the lower rates set for younger workers -- for fear of further job losses.

The Living Wage Foundation said, however, that the steep increase in its voluntary rate was needed to reflect recent price increases and "evolving perceptions of what is needed for a decent standard of living". It bases its calculation on a basket of goods and services seen by the public as necessary for a socially acceptable standard of living.

Official data on inflation, published on Wednesday, is set to show how sharply prices have risen over the past year for essentials that make up a bigger share of household budgets for those on low incomes.

In recent years, people's expectations of living standards have also risen -- to include, for example, a bigger budget for after school clubs and weekend family activities. The Foundation has also changed its methodology to allow for a bigger food budget, and for the fact that single parents and second earners in families with children rarely work full-time.

UK's 'real living wage' to rise almost 7%