Jeremy Corbyn suggested a Europe-wide minimum wage could help regulate the number of migrants coming to Britain to work.
And in his first major speech of the referendum campaign, the Labour leader denied his support for Britain to stay in the Europe had been 'half-hearted'
Mr Corbyn said the volume of economic migrants coming to the UK wasn't the problem, it was a lack of regulation on wages between nations.
He said: "I don't think too many have come, I think the issue has to be of wages and regulations.
He added: "There has to be a case for a minimum wage tied to the cost of living across the continent.
"There is nothing wrong with people wanting to migrate to work around the continent, but there has to be a level playing field on pay and conditions."
In a speech which touched on many of the Labour leader's favourite topics - including nationalisation of railways and tax avoidance - he warned that it's the Tory government, not the EU which is failing Britain.
The Labour leader said crises like that gripping the steel industry are “global problems” which must be addressed at an international level.
And he called on left-wing voters who are disenchanted with Brussels to train their guns on the Tories instead.
“There is a strong socialist case for staying in the European Union,” Mr Corbyn he said.
“It is sometimes easier to blame the EU, or worse to blame foreigners, than to face up to our own problems - at the head of which right now is a Conservative government that is failing the people of Britain.”
The Labour leader seemed relaxed as he delivered his first foray into the EU debate - some eight weeks after the campaign began.
Wearing a linen shirt and open collar, he opened with a joke about the venue for the speech, London's Senate House, having been the inspiration for the Ministry of Truth in George Orwell's 1984.
He joked: "We'll see."
But he said that despite his late entry into the debate - and the Euroscepticism he displayed earlier in his career - his support was not 'half hearted'.
Mr Corbyn said: "There's nothing half-hearted about what we're doing. We're putting forward a political agenda about social justice in this country, about driving down tax evasion in this country.
"But we're also putting the international case about human rights and justice all across Europe. That's what we're doing and you'll hear plenty from us on this. There's nothing half-hearted about what I do.
He launched an attack on Tory MEPs for failing to use their position in the European Parliament to crack down on tax avoidance.
He said: "On six different occasions since the beginning of last year Conservative MEPs have voted down attempts to take action against tax dodging.
"Labour has allies across Europe prepared to take on this global network of the corrupt and we will work with them to clamp down on those determined to suck wealth out of our economies and the pockets of our people."
Answering questions after the speech, he accepted public concern about the number of migrants using EU free movement rules to come to the UK for work.
