Big shifts in men's working patterns over the last 20 years have seen increasing numbers working part-time, a new study shows.

Almost one in eight men works part-time today, compared with fewer than one in 12 two decades ago, said the Resolution Foundation.

The think tank said more men in lower paid roles are working fewer hours or part-time, while higher paid men are working more.

These changes have led to a 'hollowing out' of the male labour force, with fewer middle earners.

The share of low-paid men earning less than £175 a week (a third of the typical male weekly wage) has increased by 70 per cent over the last 20 years, while the share of higher-paid men earning more than £1,060 (double the typical weekly wage) has increased by 15 per cent, the research found.

In contrast, the share of middle-earning men, earning between £400 and £660, has fallen by 15 per cent.

The foundation said it had discovered a growing divide in the number of hours that men working full-time do.

The average number of hours worked by low-paid men has fallen from 44.3 hours in 1997 to 42.2 hours in 2016, while increasing by 0.5 hours to 37.3 hours for high-paid men.

Taking these two trends together, low-paid men now work fewer hours on average than higher-paid men (34.1 hours, compared to 36 hours), a reversal of working patterns from 20 years ago.

There has been no such hollowing out female workers, with the big change over the last 20 years being a small rise in the share of higher paid women, while both part-time and full-time women have increased their hours over the last 20 years.

Stephen Clarke, policy analyst at the Resolution Foundation, said: "When people talk about the labour market 'hollowing out' they're normally referring to mid-skilled jobs moving to other parts of the world, or disappearing altogether as a result of automation.

"But Britain's real hollowing out problem has much more to do with the hours people are working than the rates of pay different jobs bring.

"The increase in earnings inequality among men is about the increasing number of low-paid men who are either reducing their hours or moving into part-time work, in some cases against their wishes.

"Stronger pay rises and finding work will always be the best and most direct way for households to boost their incomes.

"But being able to work the hours you want or need to get by also matter hugely.

"Women still dominate part time and low-paid work but men are increasingly joining them.

"For the sake of both sexes we should be concerned about the numbers who find themselves there when they desperately need a full-time job."