Nigel Farage said Monday that British Prime Minister Theresa May's agreement to leave the European Union was "madness."

Britain will leave the EU after its leaders approved the agreement on Sunday, marking the first time that one of the 28 members will exit the bloc.

Farage, former chairman of the United Kingdom Independence Party and one of the key figures behind Brexit, said on America's Newsroom that leaving the EU gives Britain less sovereignty.

"It looks like the worst deal in history to me," he said. "[Britain] has signed up for purgatory. It's madness."

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Farage said that May signed up for an agreement that would give away too much of the country's money, while having to accept EU rules without any say.

"We don't get back, at this stage of the game, control of our borders," he said. "We're not able, for some years, to do trade deals."

He added that Britain has now been signed up to became "rule-takers" from the EU.

"It's a bad deal. It's the worst deal in history, and I very much hope the British parliament votes it down," Farage said.

He said that May is "trying to please both sides" with her agreement to leave.

"It's sort of half in, half out. Never-never land. The prospects of a trade deal between us and the USA have been kicked way, way into the future."

Watch more from America's Newsroom above.

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