Keir Starmer has labelled Reform’s migration policy as "racist and immoral" for wanting to remove people who are "lawfully here".
When asked whether he thinks the Reform plan to deport migrants is an "immoral policy", Sir Keir agreed.
He added: "We are a proud, tolerant country," adding that people have been coming to the UK "for centuries".
The Prime Minister agreed that he believes illegal migrants should be removed, but claims illegal deportations are a "completely different thing," adding, "to reach into people who are lawfully here and start removing them."
Speaking to the BBC, he said: "I do think that it is a racist policy. I do think it is immoral. It needs to be called out for what it is."
"I think there are plenty of people who vote Reform or thinking of voting Reform who are frustrated."
Reform UK's Zia Yusuf hit back at the Prime Minister's criticism, accusing Labour of threatening to brand anyone opposing welfare access for foreign nationals as racist.
Reform UK’s Head of Policy said: "Labour’s message to the country is clear: pay hundreds of billions for foreign nationals to live off the state forever or Labour will call you racist.
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Keir Starmer has labelled Reform’s migration policy as 'racist and immoral' for wanting to remove people who are 'lawfully here'
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He added: "Reform’s plan will ensure only British people can access welfare and that migrants contribute to society."
Reform UK's leader, Nigel Farage, unveiled the controversial proposal last week, which would eliminate the current system allowing migrants to secure permanent residency after five years.
The party's plan would require migrants to repeatedly apply for new visas under stricter criteria, effectively ending the pathway to permanent settlement that currently exists.
Labour's approach differs significantly, with plans to extend the qualifying period for indefinite leave to remain from five to ten years.
Sir Keir drew a clear distinction between Reform UK's policies and its supporters
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The Government launched a consultation on this change in May as part of broader measures to reduce immigration numbers.
The existing system permits migrants to apply for permanent residency after five years, granting them the right to live, work and study in Britain indefinitely.
Sir Keir drew a clear distinction between Reform UK's policies and its supporters, suggesting voters were responding to years of Conservative government failures rather than embracing racist ideology.
The Prime Minister acknowledged these voters' concerns, noting that after fourteen years of stagnant living standards and deteriorating public services, their desire for rapid change was understandable.
Reform UK's Zia Yusuf hit back at the Prime Minister's criticism
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He emphasised that many Reform supporters might have previously backed Labour and were simply impatient for improvements to materialise.
Public sentiment appears split on the issue.
YouGov polling reveals 58 per cent oppose removing indefinite leave from current holders.
However, 44 per cent support ending the policy entirely, whilst 43 per cent oppose such a move.