EU negotiator Maros Sefcovic has said it is "high time we got Brexit done" and accused the UK of trying to hold talks with "a gun on the table".
The European Commission Vice President branded Boris Johnson's plan to rip up his own Brexit deal "illegal" and said the proposed legislation had set talks back "two years".
Mr Sefcovic said the war in Ukraine showed the UK and EU are "natural allies" but argued that the British Government's demands were "unrealistic and unfair".
In a speech to Bloomberg in London, Mr Sefcovic alluded to David Cameron's speech in the same place in 2013 which paved the way for the Brexit referendum.
He joked: "I hope we are close to reaching the end of this particular cycle.
"You may not hear this often from the European Commissioner but it is high time we got Brexit done."
Mr Johnson famously won a massive majority on a ticket to 'Get Brexit Done' but the reality is the row is far from over more than two years on for his 2019 election pledge.
But he tore into the Prime Minister over new legislation, which hands the UK power override parts of the post-Brexit trade pact in Northern Ireland.
Mr Sefcovic said: "We are ready to negotiate but we need the acknowledgement that what needs to be done will be a genuine negotiation.
"It shouldn't be some kind of window dressing. Okay we've met, we took a picture, we negotiated but there could only be one outcome of this negotiation and this is what is written in the bill.
"Because I mean you are not going to negotiate when you have a gun on the table."
Mr Sefcovic said he hadn't met with Foreign Secretary Liz Truss since February and he'd had "radio silence" from the UK until Ms Truss told him they were tabling the bill.
The Northern Ireland Protocol bill, which received its second reading in the Commons this week, has enraged Brussels and some MPs who believe it breaks international law.
Ms Truss argued it has "strong legal justification" and is necessary to resolve trade wrangles in Northern Ireland.
