The SNP has demanded the UK Government reforms the national minimum wage after research suggested younger workers could end up more than £9,500 worse off than their older colleagues by the end of the year.

Figures highlighted by the party show that under the existing set-up, staff aged 18 to 20 working for the minimum wage full-time over the course of this year would have earned £13,865, while those aged 23 and over would have earned £19,288 – a difference of £5,423.

The minimum wage for people aged 18 to 20 currently stands at £7.49 an hour while for people aged 23 and over it is £10.42. Between January and March this year the rates stood at £6.83 and £9.50 respectively.

Minimum pay workers aged 16 and 17 would have earned the even lower amount of £9,772 over the last 12 months and banked £9,516 less than colleagues aged 23 and over, according to figures from the House of Commons Library.

The minimum wage for people aged 16 and 17 is currently £5.28 an hour, up from the previous rate of £4.81 between January and March this year.

The SNP has described the existing arrangements as “age discrimination” and demanded the UK Government revises its legislation to ensure all ages are paid what it termed “a real living wage” to stop younger people losing out.

Mhairi Black, the SNP’s deputy leader at Westminster, said alternatively the UK Government could devolve the power to set minimum pay rates and the Scottish Government would bring in the changes instead.

The MP for Paisley and Renfrewshire North said: “People doing the same job should be paid the same wage – no matter their age.

“It is disgusting that 16 to 20-year-old workers can be over £5,000 worse off just for being younger.

“It is time for the out-of-touch Westminster Government to recognise it’s the 21st century and end age discrimination in UK pay levels for good by bringing in a real living wage for all.

“If they won’t, then they must devolve the key powers to Scotland so we can.

“The Scottish Government has already helped to ensure that a record 91% of employees over 18 earned the real living wage or more in Scotland – higher than the UK as a whole and any other UK country.

“People need a real living wage now more than ever, after 13 years of Tory austerity and as Westminster’s cost-of-living crisis continues.

“People in Scotland shouldn’t have to wait for a Westminster Government they didn’t vote for to act – we need full powers to do what is right.”

A UK Government spokesperson said: “We are committed to building an economy that works for everyone and ensuring that young workers are paid fairly without damaging their employment prospects.

“From April 1 next year, we will increase the national living wage by almost 10% to £11.44 an hour and extend it to 21 to 22-year-olds, a record cash increase that will end low hourly pay for those aged 21 and over.”