European Union Commission President Jean-Claude Juncker | Thierry Charlier/AFP via Getty Images Jean-Claude Juncker: ‘English is losing importance’ The European Commission president opted to deliver a speech in Florence in French.

FLORENCE — Jean-Claude Juncker, the European Commission president, opted to deliver a speech in French on Friday morning because he said "English is losing importance" in Europe.

He gave the comments, which are unlikely to mend fences after a war of words between Brussels and London over Brexit negotiations, at the "State of the Union" conference in Florence’s Palazzo Vecchio — an annual event for European dignitaries.

Juncker said he was opting for French because “slowly but surely English is losing importance in Europe and France has elections this Sunday and I want the French people to understand what I am saying about the importance of the EU.”

The Commission president tackled the row that erupted over a private meeting he had with U.K. Prime Minister Theresa May last week. Following the meeting Juncker reportedly said: “I leave Downing Street 10 times more skeptical than I was before.” May gave a speech on the steps of Downing Street on Thursday in which she said some in Europe were trying influence the British election.

In Florence, Juncker said, “[Brexit] is no small event. Of course we will negotiate with our British friends in full transparency. But there should be no doubt whatsoever about the idea that it is the EU that is abandoning the U.K. It is the opposite in fact. It is the U.K. that is abandoning the EU.”

European Parliament President Antonio Tajani offered his full support to EU Brexit negotiator Michel Barnier and attempted to tone down the verbal joust with London.

“There is no ill will toward them. No one wants to interfere in the election of the U.K,” he said. Tajani said the EU simply wants a stable government it can negotiate with. “It would be detrimental to everyone were we not capable of reaching an agreement,” Tajani said.

The EU's chief Brexit negotiator Michel Barnier said he would deliver his speech in English. “Obviously I want to be understood by the French, but it is equally important than I am understood by the British people,” he said.

While defending the value of EU labor mobility, Barnier suggested the U.K. was to blame for its toxic immigration debate: “In 2004, the U.K. was one of very few countries that immediately opened its labor market to the new member countries.”

Barnier suggested that the immigration concerns of Europeans need to be taken seriously, but that the “solution lies in a fairer labor market” and “better training” not in ending the EU’s system of freedom of movement.

“Let me be clear. The integrity of the single market will never ever be compromised during these negotiations,” he said.

On the situation for EU citizens living in the U.K. post-Brexit, Barnier said there would need to be a role for the European Court of Justice to guarantee their rights.

“Protection should apply for the lifetime of the citizens who are concerned,” he said. That includes when those citizens do not have an existing proof of their residency, and the rights of family members should also be protected even if they are not EU citizens.

“The level of protection afforded by EU law must not be watered down. Brexit should not alter the nature of people’s daily lives,” he said.