Michel Barnier has warned that France could follow the UK out of the EU, as polls show growing support for the Eurosceptic Marine Le Pen.
He said there was “social unrest and anger” over immigration and Europe’s failure to defend its borders and for the “red tape and complexity” of the EU.
“We could draw some lessons from Brexit for ourselves. It’s now too late for the UK but not for us,” the former EU chief negotiator said.
“We can find, not just in the UK, but here in France, in the northern regions […] citizens who want to leave the EU,” Mr Barnier, who has returned to domestic politics, said.
He added, “It is our responsibility to understand why the British left […] it’s important for us to listen to the anger that was expressed in the UK, and to implement the kind of changes that are necessary to better understand and reassure the European citizens that remain.”
Latest IFOP polling shows that Ms Le Pen, who leads the National Rally party, would beat the pro-EU Emmanuel Macron by two percentage points in the first round of next year’s presidential elections.
Mr Macron is predicted to win in the second round by 54 percent to 46 percent but that is narrower than the 66.1 percent to 34.6 percent defeat she suffered four years ago.
Ms Le Pen called for Frexit in that election but has since stopped campaigning for France to leave the bloc. Instead she wants to create a “Europe of nations”.
Mr Barnier hopes to rebuild support for the centre-Right Républicains party ahead of the elections.
He was speaking at an event on Brexit in Northern France, where fishermen are complaining they have not yet got fishing licences from the UK since Brexit.
Clément Beaune, France’s Europe Minister, said the EU was accused of “being weak and slow”.
He said that the bloc should take heart from its robust approach to the Brexit negotiations.
“Back in 2016 people thought that this was the beginning of the end for Europe, but we have been able to show that we can be agile, that we can react, that we can be consistent in defending our interests in a firm way to defend the greatest European assets – the Single Market and our political unity.”
He added: “These are lessons that we must all keep in mind as Europe is facing more difficulties.”
The European Commission warned Britain that any further unilateral action over the Northern Ireland Protocol was unacceptable at a meeting on Thursday night.
Maros Sefcovic, the commission vice-president, told Lord Frost that “solutions can only be found through joint actions and through joint bodies”.
Britain insists that its unilateral actions in extending the grace periods on food products and parcels is lawful and made in good faith.
The meeting over the implementation of new post-Brexit customs arrangements in Northern Ireland was said to be “constructive” by both sides.