Boris Johnson has claimed a leaked Treasury document about checks on the Northern Ireland border is "wrong".
Labour leader Jeremy Corbyn obtained the document, claiming it proves there will be customs checks between Great Britain and Northern Ireland after Brexit.
Speaking to Sophy Ridge on Sunday, Mr Johnson said: "[This deal] allows the whole of the UK to come out of the EU including Northern Ireland and the only checks that there would be, would be if something was coming from GB via Northern Ireland and was going on to the Republic, then there might be checks at the border into Northern Ireland."
Pressed on the document talking about "checks both ways", he said "that's wrong because there won't be checks".
Answering a question about whether the document was wrong, he said: "Yes. Because there's no question of there being checks on goods going NI/GB or GB/NI because they are part of - if you look at what the deal is, we're part of the same customs territory and it's very clear that there should be unfettered access between Northern Ireland and the rest of GB.
"We're a UK government, why would we put checks on goods going from NI to GB or GB to NI? It doesn't make sense.
"So the issue is how to avoid a hard border in Northern Ireland and we can do that by making sure that there are - by having some checks on goods that might be preceding into the Republic."
However, there is confusion around his argument on the basis that the end point of many goods could not be known at the point they cross the Irish Sea.
The border in Northern Ireland has been a point of contention since the start of Brexit talks, with the so-called backstop arrangement being the main reason Theresa May's deal to leave the EU failed to pass through the House of Commons.
Mr Johnson's deal removes the backstop but adds checks in at different points.
In the interview with Sophy Ridge, Mr Johnson also gave a guarantee that he would reduce immigration figures with a points-style system, despite the same kind of system leading to an increase in Australia.
"Numbers will come down because we'll be able to control the system in that way," he told Sky News.
"And what I don't think is right is to have an uncontrolled and unlimited approach to that."
His suggestion was challenged by Labour's shadow health secretary Jon Ashworth, who said there should be a closer link to employment needs to ensure there isn't a lack of nurses or care workers, going on to say the social care system would collapse without migrant workers.
Mr Ashworth said of Mr Johnson: "He's also misleading the British people, because he's trying to give them the impression that he's going to be bringing immigration down, but when you look at the details of what he's announced today, he's saying he's going to hand over decisions on who will get a visa to an independent committee."
On Labour's Brexit plan, Mr Ashworth said he believes the best thing for Britain is to remain in the EU, but accepted the argument was lost the first time around.
He said the country should be brought together and told "this is what leave looks like, it's a credible leave, but here's remain too".
Liberal Democrat leader Jo Swinson told Sophy Ridge on Sunday she would not quit if the party fails to make gains in the election on Thursday.
Polls suggest Ms Swinson, who has been in the post for four months, could return just one extra MP compared with the Lib Dems' 2017 total.
She also denied that the party's manifesto pledge to revoke Article 50 without a second referendum was unpopular and undemocratic.
She said: "It's doing it through an election, so it is only in the circumstances where we win a majority which would be a democratic event, which I think many people would recognise would be an electoral earthquake and therefore would have democratic legitimacy."
Despite her party's own remain alliance with parties including the Greens and Plaid Cymru, she said the electorate was now faced with a "cosy stitch-up" between Nigel Farage and Mr Johnson, after the Brexit Party stood down 318 candidates in seats won by the Conservatives in 2017.
But Mr Farage answered that by saying he had done his best to stop a second referendum, and argued against his former MEPs, who resigned the whip this week, saying the Brexit Party's tactics mean Lib Dems could get in.
He also reiterated issues over trust with Mr Johnson and his immigration pledges.
He told Sophy Ridge on Sunday: "They're (Tories) beginning to say the same things, the problem is they'll make no real commitment to cut the numbers coming in and this is the fourth Conservative manifesto in a row promising to reduce numbers."
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