European Commission President Jean-Claude Juncker declared in a flagship speech Wednesday that "wind is back in Europe's sails" after last year's shock Brexit vote, an act he warned Britain would regret.
In his annual State of the Union address, Juncker urged the bloc to seize a "window of opportunity" and use the momentum from its recent economic recovery to become more deeply integrated than ever before.
Defying the eurosceptic trends that drove Britain to become the first country to decide to leave the EU, Juncker outlined a vision of a bigger eurozone and passport-free Schengen area, under the aegis of a single EU president.
The former Luxembourg prime minister also painted a picture of a Europe that would sign new trade deals around the world, although he made no mention of any such pact with Britain after it jumps ship.
"The wind is back in Europe's sails," Juncker told the European Parliament in Strasbourg, in an unrepentantly federalist speech that mixed English, French and German.
"We have now a window of opportunity but it will not stay open forever. Let us make the most of the momentum, catch the wind in our sails."
Juncker called for the leaders of the remaining 27 countries to hold a special summit in Romania on March 30, 2019 -- the day after Britain's departure, to "sail away from the harbour".
- 'You will regret it' -
Juncker did not utter the word "Brexit" until the very end of his 80-minute speech, saying only that "we will regret it" -- and then adding "you will regret it too" when British eurosceptics in the chamber jeered him.
"We will move forward -- because Brexit is not everything, because Brexit is not the future of Europe," the veteran politician added.
British eurosceptic leader Nigel Farage, who is a Euro-MP, responded to Juncker: "Thank God we're leaving -- you've learnt nothing from Brexit".
British Prime Minister Theresa May's office said she had not watched the speech, but added that "the EU will of course want to make its plans going forward" and that Britain wanted a "successful and prosperous Europe."
The 62-year-old Juncker has two years left in office as head of the EU's powerful executive to ensure that his legacy is not limited to Brexit.
While he admitted that when he gave his 2016 speech the EU was "battered and bruised by a year that shook our very foundations", this year he struck a far more optimistic tone.
With all 28 EU countries back in growth after years of economic crisis, and the populist surge of Brexit and the election of US President Donald Trump at bay for now, Juncker said there were reasons to be cheerful.
He called on the bloc to seal trade agreements with Australia and New Zealand by the end of his mandate, and push for pacts with Mexico and South American countries.
Juncker proposed a elected "single president" to lead the EU, merging his job as head of the European Commission and the president of the European Council of member states, currently held by Donald Tusk.
That idea ran into immediate opposition from Denmark and the Netherlands, while Tusk tweeted that the focus should be on "real pressing problems."
- More Europe -
Juncker's speech was full of calls for "more Europe", especially his suggestion that Bulgaria, Romania and Croatia should all finally become full members of the Schengen zone.
The eurozone should meanwhile be expanded beyond its current 19 countries, in line with the EU's treaties that say all states must join the single currency, he said.
Juncker furthermore backed French President Emmanuel Macron's call for a pan-European finance minister to help firefight future crises, although he was against Macron's proposal for a eurozone parliament.
The calls for more integration come despite the need to heal a deepening split with eastern European countries that resist such plans.
Juncker took a swipe at Poland and Hungary -- which have been at odds with Brussels over democratic standards -- saying EU countries should not be allowed to breach the "rule of law".
Turkey was also in his crosshairs as he ruled out EU membership "for the foreseeable future" because of President Recep Tayyip Erdogan's post-coup attempt crackdown, and urged Ankara to free detained journalists.
Juncker also attacked the "scandalous" conditions for migrants in Libya, with which the EU is working to try to stop Mediterranean crossings, and called for more solidarity with states like Italy that are on the frontline of Europe's migration crisis.