Party leader Jeremy Corbyn refused to answer questions about the issue as he arrived for the meeting in central London, saying only that the final policy statement would be "transformative to the lives of people all over this country."
Party officials in September backed a radical policy of expanding the rights of people to live and work in the U.K., including granting all residents the right to vote. But some Labour members suggest putting such language in the party's election manifesto would be politically damaging because many people voted for Brexit because they were uneasy about uncontrolled immigration from the EU.
"I think the public voted for change in the way the immigration arrangements work with Europe," Greater Manchester Mayor Andy Burnham told Sky News on Saturday.
"To deny that, I think, would be to deny what many people were saying when they went to vote in 2016, and that's just, in my view, a fact. It doesn't help politicians, it doesn't help Parliament, if they look like they're kind of cocooned away from that public view."
As a European Union member, the U.K. is required to permit the free movement of labor within the bloc, meaning all citizens of other EU countries have the right to live and work in the country. The same rights apply for British citizens to live and work elsewhere in the EU.
Immigration has been a central issue in the debate over EU membership. While Brexit supporters argue that Britain needs to regain control of its borders to protect jobs and communities, supporters of continued ties with Europe contend that immigrants are essential to the country's economic health and vitality.
It isn't clear exactly when Labour will release its manifesto, with party leaders trying to control the release of any details until they are formally unveiled.
Meanwhile, London's Metropolitan Police Service said Saturday that it is investigating "two allegations of electoral fraud and malpractice."
The investigation follows a request from a senior Labour Party figure, Charlie Falconer, who asked authorities to look into allegations that Brexit Party candidates were offered jobs or peerages if they would agree not to run against members of the governing Conservative Party in the election on Dec. 12.
Brexit Party candidate Ann Widdecombe told the BBC she had been offered a role in the next stage of Brexit negotiations if she would step aside. Party leader Nigel Farage alleges that people working for Prime Minister Boris Johnson told senior party members they could be made peers if they persuaded him to withdraw more of his candidates.
The Brexit Party's performance in the election could be pivotal to the result because the Brexit debate cuts across traditional party lines. By running against Conservative candidates, the Brexit Party risks splitting the pro-Brexit vote and helping candidates that want Britain to remain in the EU.
That could potentially deny the Conservatives a majority in the House of Commons, hampering Johnson's effort to push his withdrawal deal through Parliament.
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