One in six workers has been "stuck" on low pay for at least a year, new research has revealed.
A study of official figures by the Centre for Economic and Social Inclusion (CESI) found that a third of low-paid workers have seen their wages increase by less than the national average.
The report said low-paid workers receiving training on the job enjoyed bigger wage rises.
Tony Wilson, director of policy at the CESI, said: "We spend £2.9 billion a year on mainstream employment and skills support, yet virtually none of this is used to support people in low-paid work to increase their earnings. This is despite falls in real wages, a growth in insecure work and record levels of working poverty.
"Much of this funding could be unlocked straight away, simply by allowing skills providers to use their budgets to support workers most at risk of being stuck in low pay."
Mubin Haq, of the Trust for London, which commissioned the study, said: " This research demonstrates the scale of the challenge on low pay and living standards, both in London and the UK. Encouraging employers to pay the London Living Wage must be central to addressing this.
"These challenges are acute in London, with one in seven Londoners stuck in low pay for more than a year and increasing numbers working in the lowest paid jobs."