Around one in 20 worked at least 15 extra hours a week, said the report.
Midwives, social workers and school support staff were among those most likely to put in unpaid overtime, said the GMB. Unions are campaigning for the Government to end its cap on public sector pay.
Rehana Azam, the GMB’s national secretary for public services, said: “Chancellor Philip Hammond says that public sector workers are ‘overpaid’, but these shocking new figures show just how out of touch he is.
“Public sector workers are the backbone of our society, working above and beyond their contracted hours because they are committed to jobs they love.
“Yet the Government rewards their dedication with crippling real-terms pay cuts.
“Ministers think they can push staff indefinitely, but low pay, unmanageable workloads and stress are pushing many of our members to the limit.
“Unpaid hours mean that thousands are effectively earning below the minimum wage, especially in the care sector.
“The reality is that public services are held together by the devotion of overworked and underappreciated employees, who are effectively handing the Government £11bn worth of their labour for free.
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“It’s frankly patronising and ill-informed to dismiss calls for wages increases when millions of salaries would rise by a quarter if payslips genuinely reflected all hours worked.
“It’s time to tackle ever rising workloads and give our public sector workers the real pay rises they desperately need and deserve.”
PA
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