EU Remain vote will protect workers, says Labour
The only way to ensure UK workers' rights are protected is for Britain to remain a member of the European Union, Labour's deputy leader has said.
Tom Watson said the party was "united" on Europe, with 213 of its 231 MPs backing the Remain campaign.
He claimed Tory "Brexiters" wanted to take workers' rights away and urged undecided Labour MPs to back the EU.
But Vote Leave's Labour chairwoman Gisela Stuart said workers' rights had been "hard won" in the UK, not Europe.
Conservative PM David Cameron backs remaining in the EU but many of his MPs will vote to leave it on 23 June.
Jeremy Corbyn, regarded as the most Eurosceptic Labour leader for 30 years, has so far played a low-key role in the campaign.
In his speech in Coventry, Mr Watson said Mr Corbyn would be "making a major speech very soon setting out in more detail why we should remain".
He said he "respectfully disagreed" with those Labour MPs campaigning to leave the EU and urged those who were undecided to "do the right thing by disagreeing with them and agreeing with me".
Mr Watson said the EU had "protected, enhanced and extended the rights of working people in the UK for a generation or more" on paid holiday, paternity and maternity leave, rights for part-time agency workers, working hours and equal pay for women.
"There is no guarantee that those protections will remain in place if the Leave campaigners win the argument and the UK votes to leave the EU," Mr Watson said.
He said Conservatives had opposed the EU's social chapter and claimed "the Tories and the UKIPers and the Brexiters reserve a special sort of disdain for any rules that make the workplace safer".
"My message to anyone who thinks they wouldn't shelve these protections is a blunt one: Don't be so naive. The Tories are itching to get rid of them."
Although Prime Minister David Cameron and his government are campaigning to remain in the EU - four Conservative cabinet ministers and more than 100 Conservative MPs are backing the Exit campaign.
Some Conservative MPs have been angered by the government's decision to put out a 16-page leaflet promoting the UK's EU membership to 27 million homes from next week.
Earlier Bernard Jenkin MP told BBC Radio 4's World at One Mr Cameron was trying to lead the party "in a direction the Conservative Party fundamentally does not want to go".
"How many Conservative MPs would be for Remain if George Osborne and David Cameron themselves were for Leave? Probably not much more than a dozen, or two dozen. The idea that the Conservative Party is evenly split on the European question is wrong."
Meanwhile Vote Leave is backed by a number of Labour MPs, including Gisela Stuart and Labour-supporting businessman John Mills while Grassroots Out's supporters include Labour's Kate Hoey and former Respect MP George Galloway.
Responding to Mr Watson's speech, Ms Stuart said: "Workers' rights are not something that have been gifted to us by the EU, they have been hard won here at home and should be protected by a Parliament that is properly accountable to voters in the UK.
"We have seen in Greece how easily the EU discards with social protections when it is inconvenient to them. If we want to take back control of our economy, our democracy and the £350m we hand to Brussels each week the only safe option is to Vote Leave."
The Trade Union and Socialist Coalition has also launched a bid to be designated as the official campaign to get Britain out of the European Union but the TUC, the main umbrella group for Britain's trade unions, backs staying in the EU.