PRIME MINISTER Theresa May is allowing bosses to “treat workers like disposable labour,” TUC leader Frances O’Grady said yesterday as official figures revealed that the number of zero-hours contracts had shot up by 13 per cent in the last year.

The number of people relying on the super-exploitative arrangement, under which workers have to be available to work but bosses are under no obligation to provide it, has now reached 905,000.

The TUC says median pay for a zero-hours worker is a third less an hour than for an average employee.

Ms O’Grady called for employment laws to be “dragged into the 21st century.”

Unison general secretary Dave Prentis pointed to the prevalence of zero-hours contracts among low-paid care workers.

“They give the upper hand to unscrupulous employers and silence employees who fear they’ll lose hours if they speak out about poor practice or illegal pay,” he said.

“Councils must stop ignoring the use of zero-hours in the care sector and end the damage they cause to both care staff and the people they support.”

GMB leader Tim Roache stormed: “In the real world, zero-hours means zero certainty, zero security, zero ability to plan your life, your future, your family’s finances because, from one week to the next, people don’t know how much is going to be on their next payslip.”

The steep rise in this precarious form of employment accounts to a large extent for the official jobless total falling by 31,000 in the three months to January to 1.58 million, the lowest for a decade.

Though average earnings increased by 2.2 per cent in the year to January, the increase was down by 0.4 percentage points on the previous month’s figure.

Employment Minister Damian Hinds claimed the figures showed “good news for hardworking families” and that the government would be “pressing ahead with our welfare reforms to ensure that it always pays to be in work.”

But Labour shadow work and pensions secretary Debbie Abrahams warned: “We welcome the overall increase in employment but are deeply concerned that millions remain in low-paid, insecure work.

“The government has also failed to close the employment gap faced by women, disabled people and ethnic-minority groups, who are all less likely to be in work.

“Labour would reverse cuts to in-work support that could see working families lose £2,600 a year, ban the exploitative zero-hours contracts being used on hundreds of thousands of workers and guarantee a real living wage.”