Sir Keir Starmer has signalled his government is planning to change the way human rights laws are applied to tackle the challenge of “mass migration”.
The Prime Minister said Downing Street would “look again” at how international laws are interpreted by UK courts.
He was asked on BBC Radio 4’s Today programme about a Brazilian paedophile who successfully claimed he would be treated worse in a Brazilian prison than he would in a British prison.
Pushed on what he thought was blocking deportations of foreign criminals, Sir Keir cited Articles 3 and 8 of the ECHR - which ban torture and protect the right to private and family life respectively.
"But it's more than that, it’s the (UN) Refugee Convention, it’s the Torture Convention, the Convention on the Rights of the Child.
“I’m not going to tear all that down. I believe in those instruments, I believe in the rule of law and I think they matter.
“But all international instruments…have to be applied in the circumstances as they are now. We’re seeing mass migration in a way that we haven’t seen in previous years.”
His comments follow Home Secretary Shabana Mahmood’s vow to set out plans to tighten rules for migrants seeking indefinite leave to remain in her speech at Labour’s party conference, which focused on how to meet the rising threat from Reform in the polls.
In a separate interview following his own keynote speech on Tuesday, the Prime Minister said Nigel Farage and his supporters are not racist despite insisting that the Reform party's immigration policy is.
The past few days have seen Sir Keir and his colleagues step up their attacks on Mr Farage's party, repeatedly branding Reform's policy to remove the right to remain from some migrants legally living in Britain as "racist" and "immoral".
The PM also declined to say US president Donald Trump's claims that London wants to "go to Sharia Law" were "racist", but described them as "nonsense".
Speaking with Sky's Beth Rigby, as part of a series of interviews following the embattled PM's keynote speech, Sir Keir said he did not believe Mr Farage was racist.
He said: "No, nor do I think Reform voters are racist.
"They're concerned about things like our borders, they're frustrated about the pace of change.
"I'm not for a moment suggesting that they are racist."
He insisted he had been talking about a "particular policy", claiming Reform's plans would see migrants who live in the UK lawfully deported, saying "that to me would tear our country apart".
The Labour leader, who described Mr Farage as a "formidable politician", declined to say whether he believed his opponent was courting racists with the policy, but said minorities in the UK felt a "shiver down their throat".
On Tuesday evening, David Lammy, the Deputy Prime Minister, appeared to row back on claims he made to the BBC that the Reform leader had "flirted with Hitler Youth".
The statement appeared to reference allegations that emerged in 2013 that Mr Farage sang Nazi songs as a schoolboy.
Mr Farage denied the allegations at the time, which stemmed from a 1981 letter reportedly written by his teacher claiming the schoolboy and others marched through a village "shouting Hitler Youth songs".
Mr Lammy said: "I'm not going to play the man. I'm playing the ball, as our leader did.
"I will leave it for the public to come to their own judgments about someone who once flirted with Hitler Youth when he was younger."
In a later interview with BBC News, Mr Lammy said the Reform leader had denied the allegations, saying: "I accept that he has denied it."
He added: "I wasn't at school with Nigel Farage. I don't know what songs he sang at school."
