Jeremy Corbyn has invited the leaders of progressive and socialist parties across the EU to London in February 2017, just a month before the UK government has promised to start formal negotiations with Brussels.
The Labour leader's continental counterparts will dine with the shadow cabinet before attending a conference on Brexit, a source close to Corbyn told IBTimes UK.
"The event will include speakers from parts of society that have not had their voices heard in the Brexit debate. This will include business, NGOs and trade unions," the source said.
The development comes after Corbyn addressed the Party of European Socialists Council in Prague, the Czech Republic, on 3 December.
He warned that the left has been seen as "apologists for a broken" system and Corbyn urged the group of left-wing leaders to "stand for real change".
"If we do, I have every confidence that the principles of solidarity, internationalism and socialism that we stand for can be at the heart of European politics in the 21st century," he added.
"That's why it is vital that our rhetoric cannot be used to legitimise the scapegoating of refugees or migrant workers.
"When we talk about refugees we need to talk about them as human beings, not as numbers, or as a burden, but instead as children, mothers, fathers, sons, daughters."
The left-winger also controversially told Sky News that Labour would seek an amendment to any Article 50 bill, draft legislation which may be needed to trigger the UK's split from the EU.
"When the Article 50 debate comes up we will put forward an amendment to it which will be on the issues I've just said on market access and protections," Corbyn said.
The comments come after England's High Court ruled that MPs must have a vote on the issue. The government is contesting the decision at the Supreme Court from 5 December.
Shadow Chancellor John McDonnell said Labour would not seek to block a Brexit, warning that such a move would put the party on the side of "corporate elites".
But an amendment to Article 50 legislation is expected to delay the process, putting Theresa May's March 2017 deadline in jeopardy.