Jeremy Corbyn has promised Labour will support a 'remain' vote at the EU referendum regardless of the outcome of David Cameron's renegotiation deal, which the left-winger branded as "largely irrelevant" during a speech in Brussels.
The Labour leader, who met with the Party of European Socialists in the European Parliament, said his party would back a pro-EU position as the 28-nation-bloc "brings investment, jobs and protection for British workers and consumers".
"The negotiations Cameron is conducting on Britain's relationship with the European Union are a theatrical sideshow, designed to appease his opponents within the Conservative party. They are not about delivering reforms that would make the EU work better for working people," Corbyn claimed.
"The Labour Party will campaign to keep Britain in Europe in the forthcoming referendum, regardless of the outcome of the talks being held in Brussels today. That is because it brings investment, jobs and protection for British workers and consumers."
The leader of the opposition also argued that the proposed emergency benefits break is "largely irrelevant". The mechanism would allow the UK apply to Brussels in a bid to block EU migrants in Britain from accessing in-work benefits for up to four years.
But as the University of Oxford's Migration Observatory has pointed out, there is no hard evidence for the claim the welfare system draws migrants to the country.
"Cameron's misnamed 'emergency brake' on migrants' in-work benefits is largely irrelevant to the problems it is supposed to address. There is no evidence that it will act as a brake on inward migration," Corbyn added.
"And it won't put a penny in the pockets of workers in Britain or stop the undercutting of UK wages by the exploitation of migrant workers.
"Cameron's negotiations are a missed opportunity to make the case for the real reforms the EU needs: democratisation, stronger workers' rights, an end to austerity and a halt to the enforced privatisation of public services."
His speech comes after top Labour MP Chuka Umunna, a member of the Home Affairs Committee, backed Cameron's 'emergency break' proposal.
"I genuinely do believe that you cannot have the free movement of people in the same way as the EU was created, where you had six nations with not too similar economies," he told a London audience on 16 February.
"Having people pay into our system with this emergency break mechanism, the prime minister is seeking, I do actually think is a good thing. We should embed the contributory principle into our social security system anyway."
Cameron is hoping to secure a settlement from EU grandees in Brussels over 18 and 19 February so he can call the referendum for 23 June. The prime minister said ahead of the negotiations that he would be "battling for Britain" and pledged not to "take a deal that does not meet what we need".
The latest opinion poll from Ipsos MORI, of more almost 500 people between 13 and 16 February, put 'remain' on 56% and 'leave' on 36%, with 10% of respondents undecided.
15:00 (GMT): Doorstep by Tusk as EU leaders arrive in Brussels
16:00: An "exchange of views" with the European Parliament President Martin Schulz
16:30: A "family photo" with the EU leaders and top civil servants
16:45: First working session on a new settlement for the UK in the EU
19:00: A working dinner to discuss the draft deal
TBC: Press conference hosted by Tusk and the European Commission President Jean-Claude Juncker
09:00: Informal working breakfast to continue the discussions on the UK (If a deal has not been reached on 18 February)