In a related video, Ed Miliband and Jeremy Corbyn unite to back Remain campaignIBTimes UK

Jeremy Corbyn will use the threat of a Conservative government negotiating the UK's exit from the EU in a bid to drum-up support among Labour voters for a Remain vote at the EU referendum. The left-wing leader is also expected to argue for the need to defend workers' rights, during a major speech at the Institute of Engineering Technology on 2 June.

"A vote to Leave means a Conservative government would then be in charge of negotiating Britain's exit. Everything they have done as a government so far means we could not rely on them to protect the workplace rights that millions rely on," Corbyn will declare.

The Labour leader will outline how membership of the 28-nation-bloc has benefited UK workers, including maternity and holiday pay rights.

"Several Leave supporters have stated clearly they want to leave Europe to water down workers' rights, to rip up the protections that protect work-life balance, that prevent discrimination and prevent exploitation and injustice," he will add.

"That is why we say, the threat to the British people is not the European Union – it is a Conservative government here in Britain, seeking to undermine the good things we have achieved in Europe and resisting changes that would benefit the ordinary people of Britain.

"A vote to leave means a Conservative government would then be in charge of negotiating Britain's exit. Everything they have done as a government so far means we could not rely on them to protect the workplace rights that millions rely on. A Tory Brexit negotiation would be a disaster for the majority of people in Britain."

The speech will come after shadow chancellor John McDonnell, a close ally of Corbyn's, claimed sharing a platform with the Conservatives on the EU referendum campaign would "discredit" Labour. "The Europe that the Tories want is not our Europe. Cameron went to negotiate away workers' rights in advance of this referendum. If he could have done it, he would have done," McDonnell said at Labour In event, according to Politics Home.

"If Cameron and his crew are still in power after this referendum they will continue dismantling our welfare state. They will continue to cut benefits, undermine wages and cut public service jobs. This will go on.

"Sharing a platform with them discredits us. It demotivates the very people we are trying to mobilise."

The 30 May comments proved controversial since Labour's new Mayor of London, Sadiq Khan, had earlier that day campaigned for a Remain vote alongside the Prime Minister David Cameron. "Sadiq won't miss a single opportunity to make it absolutely clear to those voters where Labour stands on the referendum," a spokesman for the top Labour politician later said.

Meanwhile, a small number of Labour MPs, including Graham Stringer, Gisela Stuart and Kate Hoey, have thrown their support behind a Leave vote at the 23 June ballot. German-born Stuart, the chair of Vote Leave, claimed the UK's membership of the EU has been a disaster for British workers.

"With unemployment in the double digits across the Eurozone and harsh austerity measures implemented at the expense of vital public services," she said. "The head of the In campaign Lord Rose has himself said that workers will get a pay rise if we Vote Leave. And as the Bank of England has confirmed, uncontrolled immigration has played a key role in bringing down wages."

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Labour leader and pro-EU campaigner Jeremy Corbyn Christopher Furlong/ Getty Images