One of the UK’s largest trade unions has blasted the growth in low-paid jobs and wage disparities between age groups, calling on the government to significantly increase the legal minimum wage to reflect rising living costs.

Unison is calling on the government to raise the legal minimum from £7.50 an hour for those aged 25 and over to the level of the “real living wage” – £9.75 an hour in London and £8.45 elsewhere.

In evidence submitted to the Low Pay Commission on Friday, ahead of its review of the so-called ‘National Living Wage’ (NLW), Unison also reveal that tens of thousands of public service workers are being paid less than the real living wage.

The union estimates that 163,466 full-time staff out of 2.3m directly employed in local government, the NHS, higher and further education, and sixth form colleges were paid less than the £8.45 real living wage over the past year.

However the figures are likely to be an underestimation, as they do not include those who deliver public services through private organisations in areas such as social care, cleaning and catering.

Some workers in areas such as the care sector are – even now – being denied the legal minimum wage, say Unison.

Unison also want to see all employees paid the same hourly rate, including under 25’s and apprentices.

The NLW is currently set at £7.50 an hour for workers aged 25 and over, £7.05 for 21 to 24-year-olds, £5.60 for 18 to 20-year olds, £4.05 for under-18’s and just £3.50 an hour for apprentices.

General secretary Dave Prentis said: “Poverty pay should be outlawed in the 21st century. Yet employers are still cheating staff out of their rightful earnings.

“It’s also wrong that young workers doing exactly the same job as older colleagues are paid less per hour just because of their age.

“Everyone benefits if staff are paid a decent wage. They deserve an hourly rate that reflects the real cost of living for them and their families.”

Unison is backing the Living Wage Foundation’s campaign, which is calling on employers to pay staff a country-wide living wage of £10 an hour.

A study published by Cardiff University earlier this year found that 60% of poverty-stricken households in Britain include at least one person in work.

Rod Hick, a social policy lecturer who led the research, said: “Tackling in-work poverty requires rethinking our approach – it’s about improving the circumstances of the whole household, not just those of an individual worker, and promoting employment is key.”

Hicks recommended three main policies, which he claimed would go some way to reduce in-work poverty. These are: greater provision of free and affordable childcare, a reversal of cuts to tax credits and universal credit, and measures to help reduce sky-high rents in the private sector.