A vote to Leave the European Union will put workers' rights 'immediately at risk', the Labour leader has said.

Jeremy Corbyn outlined his reasons for supporting a Remain vote at a rally with trade unionists in London.

The Labour leader used his speech to warn trade unionists and his party's supporters that if Britain exits the European Union workers' rights will be "immediately at risk" and this is why Labour voters must back the Remain campaign.

Corbyn said: "We want to defend the very many gains that have been made by trade unions across Europe that have bought us better working conditions, longer holidays, less discrimination and maternity and paternity leave.

"We believe that a Leave vote will put many of those things seriously and immediately at risk.

"Many in work will be significantly worse off when the bonfire of regulations promised by others takes place."

The Labour leader also used the speech to hit back at accusations that he has not been prominent enough in the referendum campaign.

Many believe this has led to a large section of identifiable Labour supporters who do not know the party's position on the referendum.

The Islington North MP said he is backing the EU to "defend" workers and urged his supporters to "vote Remain".

He said: "We are making the strongest case we can - from Land's End to John O'Groats, from Norwich to North Wales, we are making the case everywhere that staying in the EU gives us the opportunity to defend and extend the rights of people at work, gives us the jobs that we need and the exports we must fulfil as a country to the rest of Europe.

"Therefore we are making the strongest case we can, for the good of the ordinary people of this country, to vote to Remain to give us that voice to try to improve rights and justice in this country and all across Europe.

"It's the Labour position, it's the trade union position to vote to Remain. That's why we have come together here today to share our values, share our determination and share our strength."

The Labour leader's speech was criticised however by Labour MP Frank Fields.

Fields, who is backing Leave in the referendum, said the party will not be "pushed around" by the leadership.

He said: "The idea that Labour voters are owned by the party... and the troops will do as they are told. That may have happened in 1945 but it has long ceased to happen and it isn't going to happen this time."

The Labour MP warned if pro-Brexit-Labour voters were made to feel "unclean" about their position in the referendum they could move to Ukip and damage Labour's chances of winning the 2020 general election.

He continued: "If you are at the bottom of the pile you've paid the price... and people are saying 'it's enough, I'm fed up, it's enough, and we don't have to take it'".

"It is partly what this vote is about to say, we've borne the price of your open markets, of our wages being pushed down, of our children not being able to get houses, not being able to get into schools that they would like to, of lengthening queues in the NHS and the referendum day will be a day when they say enough is enough."