Labour MP Caroline Flint was blasted by Remainers as she blamed the rise of zero hours contracts on the EU.
Speaking in the Commons as MPs prepare for a crucial vote on Boris Johnson’s new Brexit deal, Flint was told to “cross the floor” and sit with the Tories after her intervention.
Flint, who campaigned for Remain, has refused to join the so-called rebel alliance opposing the government and is among 19 Labour MPs with strongly pro-Leave constituencies who could back the fresh agreement the PM has struck with Brussels.
“When it comes to workers’ rights, the EU isn’t God,” she said.
“The fact is local authorities up and down the UK have to outsource contracts to the European Union at the detriment of workers in their local communities.
“We have seen a rise of zero hours contracts and poor conditions partly because of that outsourcing.”
Labour Leave MPs’ support could hand Johnson a majority and see him take the UK out of the EU on October 31.
But concerns remain about whether the deal could damage workers’ rights.
Written into Johnson’s political declaration - a document which sets out the ambitions for a UK-EU trade deal - is a commitment to a “level playing field” which says that UK rights and protections will not fall below the EU’s.
But Jeremy Corbyn and Keir Starmer, Labour’s shadow Brexit secretary, say the trade deal is yet to be negotiated and that ministers have kept the freedom to diverge from the bloc on rights in the withdrawal deal.
In a further bid to woo Labour MPs on Friday night, Johnson has offered a package of promises to bolster workers rights and environmental standards in UK law after Brexit.
But Flint and other MPs, such as Melanie Onn and Gloria de Piero, have expressed public support for the deal.
It has led to Momentum boss Jon Lansman making threats to organise to deselect the rebels.
He tweeted on Friday: “Johnson’s deal will be a wrecking ball through the lives and well-being of ordinary people across Britain.
“Labour MPs cannot and must not vote for it.
“If they do, the NEC will have no choice but to replace them with a new, socialist Labour candidate at the next election.”
Intervening in SNP Westminster leader Ian Blackford’s speech, which criticised Corbyn’s discipline of MPs, Flint remarked: “I wonder if he got a section of his speech from Jon Lansman.”
Blackford replied to Flint claiming she was wrong to back the PM on workers’ rights.
He said: “I would simply say to my right honourable friend that I would trust the European Union with workers’ rights before I would trust this Conservative government.”