JEREMY Corbyn has insisted there are not too many EU migrants in Britain and that there has to be a humanitarian “attitude of mind” towards the large numbers of refugees fleeing to Europe.

Making his first major intervention in the European referendum debate, the Labour leader – criticised by some of his own colleagues for his lukewarm response to the in-out debate – told an audience of mainly students at London University’s Senate House that there was “nothing half-hearted” about the Labour In campaign.

The London MP quipped that the 1930s modernist venue for his speech was used by writer George Orwell as a model for the Ministry of Truth in his famous novel about a dystopian Britain of totalitarian control.

In a question and answer session following his speech Mr Corbyn was asked if he thought too many EU migrants had come to work and live in Britain and replied: “No, I don’t think too many have come.

“The issue has to be of wages and regulations…,” he argued. “It’s employers, who try to undercut industrywide agreements in the construction industry and others, who are the problem…There has to be a case for a minimum wage tied to the cost of living, all across the continent.”

He said there was nothing wrong with people migrating to find work across the EU but there had to be a level playing field on pay and conditions.

In 2011 David Cameron famously said, “no ifs no buts”, that his policies would get net migration in Britain to below 100,000. The Conservative Government is introducing a number of policies to reduce the pull-factor but the numbers have continued to rise; the latest annual figure for net migration is 323,000.

In response to another question, the Labour leader stressed how he was building alliances across Europe on the issue of refugees and social justice and urged the British people to view refugees not as statistics but as people.

“Every one of those people, who is shuttling now between Turkey and Greece, all of those people in refugee camps in Greece or new people in camps in Calais and Dunkirk, they’re all human beings just like you and me…I want to be part of a voice to be part of the humanitarian and human approach in dealing with this. That every European country plays its part as Germany has done in supporting and taking refugees so they can live and contribute…”

Noting how refugees had made a “massive contribution” to the life of Britain, Mr Corbyn won his loudest round of applause when he said: “You are not going to solve the refugee crisis with teargas, barbed wire, electronic surveillance and hatred; you’ll only solve it by mutual action, support and understanding of the human needs of every one of us to survive and contribute to a stronger society for everybody.”

The Labour leader has been famously opposed in previous times to the EU; he voted Out in the 1975 referendum and has expressed deeply eurosceptic views over subsequent decades.

But in his speech, he made clear, as with the case against Scottish independence and maintaining the Union, his approach was one based on socialist values; that being part of the Brussels bloc was in the best interests of the country because of issues such as workers' rights, social justice and the environment.

He stressed how there were still serious "shortcomings", which needed to be addressed by the EU such as the proposed trade deal with the US, that gave "huge cause for concern" about the potential for privatisation of public services.

But the party leader argued such failings could be better dealt with by Britain remaining in the EU "warts and all" rather than by pulling out and leaving the country at the mercy of the Conservatives.

"We have had a very big debate within the party and within the trade unions. Overwhelmingly, the Labour Party and the trade unions have come to the view that they want to campaign for a social, just Europe to protect the workers' rights that we've got, to extend them and extend that degree of justice.

"That is the position we have reached. That is the position that has been adopted by the party. That is the party that I lead and that is the position I am putting forward," declared Mr Corbyn.

Asked about the charge that he had let the pro-EU side down by his half-hearted approach to the in-out debate, he bristled and said: "There is nothing half-hearted about what we are doing, there is nothing half- hearted about our campaign, there is nothing half-hearted about our alliances.”

He went on: “I have attended a number of meetings of the Party of European Socialists, I have had lengthy conversations with prime ministers and party leaders all across Europe on the social justice case, the environmental case, the issues of climate change, trade and steel and all those issues.

"I have made numerous speeches on all these subjects. There is nothing half-hearted about what we are doing."

Stressing the need for change in Europe, the Labour leader said it was “perfectly possible to be critical and still be convinced we need to remain a member," suggesting that his own election as leader - after years at loggerheads with the direction of the party - showed what could be achieved.

"In contrast to four decades ago, the EU of today brings together most of the countries of Europe and has developed important employment, environmental and consumer protections.

"I have listened very closely to the views of trade unions, environmental groups, human rights organisations and of course to Labour Party members and supporters and fellow MPs. They are overwhelmingly convinced that we can best make a positive difference by remaining in Europe.”

Mr Corbyn added: "Britain needs to stay in the EU as the best framework for trade, manufacturing and co-operation in 21st century Europe. But we also need to make the case for reform in Europe; the reform David Cameron's Government has no interest in but plenty of others across Europe do."