has warned that Sir is "rapidly" betraying . The Reform UK leader said it would be "awful" if the Prime Minister caves in to the European Union over fishing rights in order to strike a defence deal.
The arch-Brexiteer added that he believes a security agreement with Brussels could "threaten" the Nato military alliance. Asked if Sir Keir is betraying Brexit, Mr Farage said: "It feels like it's happening quite rapidly.
"The fishing thing is a disaster, we've never got what we really voted for in any way at all from fishing, to give up more would be awful. There's now talk of a defence pact which would even include intelligence sharing at a very high level and that in my view would threaten Nato and where we're going.
"So it's almost as if the Government is trying to do two things at the same time. Number one, be big on the world stage, get on well with President Trump, but on the other reset with Brussels. And at some point, those two policies come into collision."
It comes as the PM is seeking a Brexit "reset" with the bloc and is due to host a UK-EU summit on May 19.
There have been reports that he has made concessions on fishing quotas to allow British firms to be able to bid for the new €150 billion EU defence fund as part of his push for closer ties.
Meanwhile, he is scrambling to strike a trade deal with the US to lessen the impact of Donald Trump's tariffs.
Mr Farage was speaking to the Daily Express in Dover, Kent, today as he campaigned ahead of next Thursday's local elections.
The Clacton MP rejected talk of a pact between his insurgent party and the Tories.
Shadow justice secretary Robert Jenrick vowed in a leaked recording to bring together a "coalition" of Reform and Conservative voters to take on Labour.
Reform has consistently been outperforming Kemi Badenoch's party in polling in recent months.

But Mr Farage insisted he was not worried about Sir Keir going through the middle because the right-wing vote is split between the two parties.
He said: "I think if you look at it we're already well ahead of the Conservatives in Wales, in Scotland, in the Midlands, in the north of England, we're well ahead of the Conservatives in the national opinion polls.
"I think when people realise that we are the ones to challenge the Labour Government, I think that Conservative vote will fall even further.
"Our intention isn't to do a deal with them, we feel horrifically let down by them, particularly since the 2019 general election. We aim to replace them."
Mr Farage predicted that there is a "35-45%" chance he will be the next prime minister.
He dismissed suggestions that a comeback by charismatic Tory former premier Boris Johnson could scupper his bid for power and admitted Reform's biggest threat is "ourselves".
The rebranded Brexit Party was last month at the centre of a bitter civil war over the ousting of Great Yarmouth MP Rupert Lowe.
Mr Lowe was suspended by Reform over allegations of bullying in his offices and accusations of threats of physical violence towards party chairman Zia Yusuf, which he denies.
Mr Farage said: "I don't think Boris Johnson coming back would stop anything.
"I think the biggest threat we've got is ourselves. We have to be professional, organised, disciplined, get things right.
"But you know something, politics is a big game of snakes and ladders, and there are things that happen that are way beyond your control."
Mr Farage, who went on to visit Ramsgate and Sittingbourne this afternoon, has been travelling across the country ahead of the local elections on May 1.
He said Reform "could even surprise ourselves" by how well they perform in the ballots.
Pollster and Tory peer Lord Hayward has predicted that Mr Farage's party will win between 400 and 450 seats, meaning it could end up returning the most councillors.
Reform also has the traditionally safe Labour seat of Runcorn and Helsby in its sights with a by-election taking place on the same day following the resignation of ex-MP Mike Amesbury for punching a constituent.
The Clacton MP said: "It's going to be fascinating, these are clearly going to be the most watched local elections for many, many years.
"They come four years on from a high point with the Conservatives who also won the Hartlepool by-election on the same day, a very unlikely seat for the Conservatives.
"I think Reform is going to do very well, we'll be right up there competing for the top vote share. It will be difficult to beat the Conservatives because much of it is in their shire counties. We're going to win seats, how many I don't know.
"I think that matters, but perhaps what will matter even more is the Runcorn and Helsby by-election, Labour's 16th safest seat in the country. I tell you what, boy, we are running them real close.
"A week to go, optimistic, not getting carried away, but we could even surprise ourselves how well we do."
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