One of Labour’s most senior MPs in the Midlands is at the centre of a major row with activists and union leaders after he refused to vote against the Government’s “workfare” plans in the Commons.

Liam Byrne (Lab Birmingham Hodge Hill), Labour’s Shadow Work and Pensions Secretary, has come under fire after the party instructed MPs to abstain in a vote on new laws designed to ensure that the Government can force unemployed people to take part in “back to work” programmes.

More than 40 Labour MPs defied orders from the party leadership and voted against the laws, including Birmingham MPs Richard Burden (Lab Northfield) and Roger Godsiff (Lab Hall Green), and Black Country MP David Winnick (Lab Walsall North).

Other rebels included John Healey, who was a Labour government minister in various roles from 2002 to 2010, and Nick Brown, a former Labour chief whip. Another backbencher, Gateshead MP Ian Mearns, quit his job as an aide to Labour’s Shadow International Development Secretary in protest.

The legislation, called the Jobseekers (Back to Work Schemes) Bill, was prompted by legal action taken by university graduate Cat Reilly, 24, from Birmingham, who successfully challenged the Government in the courts after she was forced to work in the Kings Heath Poundland for two weeks or lose her benefits.

Judges in the Court of Appeal ruled that the authorities had failed to give unemployed people enough information, especially about the sanctions for refusing jobs under the schemes.

It means the Government faces a potential compensation bill of £130 million for claimants who had their benefits withdrawn.

Although ministers hope to challenge the ruling in the Supreme Court, they have also introduced laws to ensure they won’t have to pay.

Mr Byrne is Labour’s spokesman on the issue in his shadow cabinet role, and was in charge of presenting the party’s case during the Commons debate – which means he has been widely blamed for the decision to abstain on the new laws, rather than voting against them.

Friends point out that Labour has supported the principle for more than a decade of applying sanctions to jobseekers who refuse to take up offers of work experience or training – and that policy is determined by the party leadership as a whole, rather than Mr Byrne on his own.

They also point out that he managed to force the Government to promise a review into the way the sanctions regime is working, following reports that job centre staff have been set targets for the number of unemployed people they penalise.

But Mr Byrne has nonetheless been widely condemned by left-wing critics, who blame him for what they see as a failure to oppose “workfare”.

They include Owen Jones, author of Chavs: The Demonization of the Working Class, who has made a number of television appearances as a left-wing commentator.

Writing on Labour List, a blog for Labour activists, he said: “Liam Byrne is also a prime example of the utter shamelessness of the British political elite. He is a politician who fuels prejudices about welfare ‘scroungers’.”

Other critics include Sunny Hundal, author of one of the leading blogs, Liberal Conspiracy.

He wrote: “I’ve had countless tweets over the last few days from Labour party members disgusted (and livid) at Liam Byrne’s stance.”

Len McClusky, General Secretary of trade union Unite also criticised the decision to abstain – although not Mr Byrne personally – in a letter thanking the rebel MPs.

He wrote: “Unite was more than disappointed with the decision taken by the Labour front bench to abstain, failing to oppose the government’s attempts to shore up its failing workfare scheme. Opposition to these measures ought to have been the response of our party.”

Mr Byrne defended himself at a meeting of Labour MPs in the Commons on Monday.

Supporters said a number of MPs spoke up to support him – but around half those who spoke were critical of the stance he took.

But he did receive backing from Rosie Winterton, Labour’s Chief Whip, who made it clear to rebel MPs that the decision to abstain on the welfare vote was taken by the entire Shadow Cabinet, including party leader Ed Miliband.

In an attempt to answer his critics, Mr Byrne wrote an article of his own for Labour List. He said Labour could not vote against the Jobseekers (Back to Work Schemes) Bill because the party supported the principle of applying “sanctions” – axing benefit – for people who refused to accept help finding work.

Referring to two schemes run by the last Labour government, called the Future Jobs Fund and the New Deal, he said: “Now as it happens, the Future Jobs Fund, which was so successful, had the same sanctions. So did the New Deal.

“Today, our key policy for getting people back to work – the Compulsory Jobs Guarantee – says that people should have the choice of a six month paid job, with training and job search, and real wages at the National Minimum Wage – and that if people don’t take up the offer of a job without good cause, they should have their Jobseekers’ Allowance stopped.

“It’s pretty hard to say Department for Work and Pensions shouldn’t have a sanction power that was well and truly incorporated into policies that worked when we were in government.”