Welcoming Prime Minister Rishi Sunak’s new agreement with the EU on post-Brexit trading arrangements in Northern Ireland, Mr Juncker said it should pave the way for the “normalising” of relations between the UK and Brussels.
However, his comments may cause irritation in Downing Street after he suggested that it gave a greater role to European institutions than some in Britain had acknowledged.
“I think that the European Commission will have more authority than it seems — and as the European Court of Justice has been reconfirmed in its role as an arbiter when it comes to internal market questions concerning Northern Ireland,” he said in an interview with LBC's Tonight with Andrew Marr.
“So, I think that although the deal is giving a response to the major British concerns, there is a part of European Union in the deal some in Britain are trying to hide.”
His statements came after Mr Johnson said he would find it “very difficult” to support the agreement finalised earlier this week in Windsor by Mr Sunak and the current commission president, Ursula von der Leyen.
Mr Juncker said a similar deal would have been available to Mr Johnson but “he was not able to acknowledge that some details of the arrangement had to be more precise”.
He said that while he liked Mr Johnson personally, he had had better relations with all the other British prime ministers he had worked with.
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“I like him as a person. He’s funny, but he’s serious nevertheless,” he said.
“Boris Johnson was a piece of work, someone you cannot categorise, in normal definitions, but I liked him as a person.”