LONDON, Sept. 28 (Xinhua) -- Half of self-employed men and women in Britain earn less than the minimum wage set by parliament, analysis by the Trades Union Congress (TUC) revealed Friday.

It means around two million men and women earn less than the national living wage of 10.23 U.S. dollars an hour, said the TUC.

Figures from the Office for National Statistics (ONS) show the number of self-employed workers has risen from 12 percent of the working age population in 2001 to the current 15 percent, with a particularly marked increase in the years after the financial crisis of a decade ago.

But the TUC said self-employed earn considerably less than those in employment and in receipt of pay packets from their bosses.

In 2017, self-employed people earned on average 16,070 dollars over the year compared with 28,219 dollars for those in employment. For self-employed, this was a pay drop compared to the previous year when they earned 17,245 dollars.

The TUC said the highest proportion of low-paid self-employed people work in farming, transport and storage and retail, with many in the so-called gig economy working on zero-hours contracts.

A TUC spokesperson said: "The TUC believes the growth in self-employment has been caused in part by an increase in sham forms of employment, where workers who would once have counted as part of a company's payroll are treated as self-employed to reduce tax liability, duck the minimum wage and deny workers their rights."

The TUC said it was concerned some self-employed workers could be in insecure or casual jobs or on zero hours contracts, with the two million people in low-paid self-employment part of at least 3.7 million people in Britain working in insecure jobs.

TUC General Secretary Frances O'Grady said: "Too many workers have been forced into sham self-employment. It's not about helping workers; it's all about companies dodging tax, ducking the minimum wage and denying workers their full rights."

"The Prime Minister Theresa May promised to change things for 'just about managing' families, but she's done nothing. She should be cracking down on businesses that use sham self-employment. She should ban zero-hours contracts. And she should give agency workers the right to equal pay to stop undercutting and encourage employers to create more permanent jobs," said O'Grady.