An EU commissioner has likened Boris Johnson, Jacob Rees-Mogg and Nigel Farage to the “Three Stooges” and issued a stern warning to Theresa May that there would be no Brexit deal next March if she insisted on sticking to her Chequers proposal.

In a speech in Ireland on Friday, Phil Hogan said the EU would fight to the end to preserve the union of nations that has stood for the past 60 years.

He said Brussels would not allow the bloc to be damaged just to save the UK “from its own silliness” and reiterated the EU position that the four freedoms forming the bedrock of the union were not negotiable. He said the only room for a special deal on deviating from the four freedoms would be in relation to Northern Ireland.

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“The EU’s first offer, reflexively rejected, was a significant departure from our internal market policy. And it was meant for Northern Ireland only. It was that Northern Ireland could remain in the single market with the EU27,” he said.

Instead of accepting that offer, the UK’s reply, he said, was “‘Let’s restrict the single market to goods and generalise it for the whole UK.’ The EU’s answer has already been given: no.

“If the UK attitude is Chequers and only Chequers, there will be no agreement before March next year on the future trade relationship,” he said.

He said that if May could not progress the UK’s position then the EU’s offer on a future trade deal would be the one it put forward months ago, “essentially a Canada-type trade arrangement”.

He added: “There is nothing new in this. Each time she is asked about her red lines, the prime minister repeats them, making a Canada-type trade deal more likely.

Hogan, who has close relations with the European commission president, Jean-Claude Juncker, said the EU would not damage its “greatest achievement” of the internal market “just to save the UK from the consequences of its own silliness”.

“Don’t be misguided by those extremists riding the wrecking ball and calling for the EU’s disappearance. Don’t be misled by the rhetoric of Mr Johnson, Mr Farage and Mr Rees-Mogg. They like to see themselves as the Three Musketeers. They are more like the Three Stooges,” said Hogan, Ireland’s commissioner in Europe responsible for agriculture and rural affairs.

In the speech to the Kennedy summer school in Wexford, he said Brexiter efforts to wreck May’s negotiations were part of an “absurdist” approach.

He said they had no policies even after two and a half years and, like populist politicians, they were “playing with a mood, not making an argument”. He added: “Their one and only idea is simple, or rather simplistic: ‘Destroy the status quo and good is sure to follow.’”

Hogan urged May not to let the Brexiters and others wreck the offer for Northern Ireland. “For an agreement to take place, the issue [of the Irish border] needs to be, as Michel Barnier said, de-dramatised. The invisible border is essential for peace – don’t listen to the Three Stooges, they don’t know the first thing about it.

“In trade terms, maintaining the invisible border will be good for the UK, good for Northern Ireland, good for Ireland, and good for the EU. Dialling down the rhetoric would allow these incontrovertible facts to come to the fore.”