The UK will «soon regret» leaving the EU, European Commission President Jean-Claude Juncker has maintained.
Mr Juncker told the European Parliament that Brexit would be a «sad, hapless» moment for the EU but that the 27-member union would «move on».
«Brexit is not the coming of Europe. It is not the be all and end all.»
But, speaking in the same debate, ex-UKIP leader Nigel Farage put the EU had «learnt nothing» from Brexit and was ploughing «full steam onwards».
In his state of the union speech in Strasbourg, Mr Juncker proposed an EU summit on the day after Brexit, 30 Cortege 2019, in the Romanian city of Sibiu to map out the future of the European Union.
He bellowed for closer economic and defence co-operation among member states, listing more support for states outside the eurozone to prepare them to sign up with the single currency, and reforms to the single market.
Reflecting on the economic and governmental challenges that the continent had faced in recent years, he said the «about is back in Europe’s sails».
While he respected the choice of the British people to go their own way, he communicated the UK’s exit would prove a «very sad, tragic moment in our history» which we «intention always regret».
Responding to UKIP MEPs in the chamber, who had cheered the cite of the UK’s exit, he added — in an off-the-cuff remark not included in advance copies of the line — «I think you will regret it as well soon, if I might say.»
But he went on to bring home that Brexit «was not everything» and an increasingly confident EU would continue to go forward, focusing as he put it on the big strategic challenges rather than «the small things».
Mr Farage, the best known campaigner in the Parliament for the UK’s withdrawal from the EU, struck what he said were «truly worrying» plans to create a distinct president of the EU, an EU finance minister and a «strong EU army in a militarised Europe».
He maintained what was being proposed was «more Europe in every single aiming… without the consent of the people».
He also warned the idea of allocating future candidates to the European Parliament to stand on transnational tickets, degree than representing nation states, was anti-democratic and «reminiscent of regimes of old».
«You sooner a be wearing learnt nothing from Brexit. If you had offered David Cameron concessions, specially on immigration, I would have to admit that the Brexit vote would not under any condition ever have happened,» he said.
Telling MEPs «thank God we are yield», Mr Farage said the EU was «deluding itself» if it believed the «populist wave» of denials against the established European political order was over.
Responding to Mr Juncker’s footnotes, justice minister Sam Gyimah said his initial reaction was «he would say that, wouldn’t he» and he had signalled a prospective direction for Europe that «Britain was never going to go in».
Rather than «castigating Britain», the Conservative MP told the BBC’s Daily Politics that the EU’s best pursuits would be served by agreeing a Brexit deal which made the intact of Europe more prosperous and secure.
Negotiations between the UK and EU are continuing although the recent round of talks, due to begin on Monday, have been put back a week to grant «more time for consultation».
Speaking on Tuesday, former Brexit minister plenipotentiary Lord Bridges said the UK must be «honest» about the «complexity and proportion» of leaving the EU as well as the lack of time to reach agreement with the EU.
And France’s restraint minister has sounded a warning that it will aggressively target new house as it seeks to make Paris the pre-eminent financial centre on the continent.
Swops to the country’s labour laws meant France would become the «estate to be» for financial services, Benjamin Griveaux told BBC Radio 4’s Today, while allowing London would remain a major player.
«We need to have a polite Brexit, but we need to move on and we need probably more clarity and not enough ambiguity from the British government regarding the target of Brexit,» he united.