In a call this afternoon, Mr Johnson told Mr Michel that solutions must be found in order to “protect peace and stability” and “safeguard the Belfast (Good Friday) Agreement in all its dimensions”, a Downing Street spokesperson said.
No 10 said the leaders agreed on “the importance of continued close cooperation and a united UK-EU response to the Russian invasion of Ukraine”.
The spokesperson said: “They also condemned the barbaric attacks on civilians, including in Mariupol over the weekend, and agreed that (Vladimir) Putin posed a grave threat to wider European security and must be stopped.
“Ahead of this week’s NATO and G7 meetings, both the Prime Minister and the President of the European Council noted the importance of maintaining pressure on the Putin regime through sanctions and providing further financial assistance to the Ukrainian government.
Prime Minister Boris Johnson (right) greets European Council President Charles Michel at the Cop26 summit at the Scottish Event Campus (SEC) in Glasgow. Picture date: Monday November 1, 2021.
Alastair Grant
European Council's President Charles Michel attends the opening ceremony for the Cop26 summit at the Scottish Event Campus (SEC) in Glasgow. Picture date: Monday November 1, 2021.
Yves Herman
“The Prime Minister also stressed the need to step-up efforts to supply additional defensive military support to Ukraine and continue to reduce the West’s reliance on Russian hydrocarbons.”
Negotiations on the Protocol have been intense for months, as it proves to be arguably the biggest hurdle in UK-EU relations post-Brexit.
Talks were initially set to last just three weeks but have dragged on, with no breakthrough in sight.
That MrJohnson has taken the decision to tackle this head-on suggests the UK side is now particularly keen to break the impasse, with Foreign Secretary Liz Truss and former Brexit Secretary David Frost having previously led talks on the Protocol.
It comes after the Prime Minister sparked backlash for comparing Brexit to the struggle faced by Ukrainians as Russian troops invade the country.
In a speech he said Brits, like Ukrainians, had the instinct "to choose freedom" and cited the 2016 vote to leave the EU as a "recent example".
He said: "I know that it's the instinct of the people of this country, like the people of Ukraine, to choose freedom, every time. I can give you a couple of famous recent examples.
"When the British people voted for Brexit in such large, large numbers, I don't believe it was because they were remotely hostile to foreigners.
"It's because they wanted to be free to do things differently and for this country to be able to run itself."
Conservative peer Lord Gavin Barwell said voting in a referendum was not "in any way comparable with risking your life" in a war, while Liberal Democrat leader Sir Ed Davey said it was an "insult" to Ukrainians.