Image copyright Getty Images Image caption Around 3,600 firms pay the voluntary living wage

More than 150,000 workers whose firms are signed up to the voluntary living wage rate are set to get a pay rise.

The voluntary rate, promoted by the Living Wage Foundation campaign group, is to rise by 30p an hour to £8.75. For those living in London, the rate will rise by 45p to £10.20 an hour.

About 3,600 firms are signed up to the scheme, including Ikea and Google.

It is separate from the government's compulsory National Minimum Wage (NMW) and the National Living Wage (NLW).

The National Living Wage, which was introduced in April last year for workers aged 25 and above, is currently set at £7.50 an hour. Those under 25, are still paid the lower National Minimum Wage.

Living Wage Foundation director Katherine Chapman urged more employers to sign up to the scheme.

"In-work poverty is today's story," she said. "The new living wage rates will bring relief for thousands of UK workers being squeezed by stagnant wages and rising inflation."

On Monday, a number of new companies announced their commitment to pay the living wage, including Heathrow Airport, the National Gallery and professional services firm JLL.

Heathrow is the first airport to sign up to the scheme. Chief executive John Holland-Kaye said paying the living wage was "the right thing to do as a responsible employer".

Research from accountancy firm KPMG on Sunday estimated around one in five UK workers were paid below the voluntary living wage.

The level of the voluntary living wage is calculated annually by the Resolution Foundation, a not-for-profit research and policy organisation.

It is overseen by the Living Wage Commission, which is appointed by the Living Wage Foundation and includes representation from employers, trade unions, civil society and independent experts.