"If the United Kingdom's sovereign decision is to leave, we regret [that], respect [it] and negotiate its departure,” he said in comments to journalists on Tuesday afternoon in Lisbon, where he was receiving the president of Peru. “If it stays for some time, we are satisfied. If the UK's decision is to remain definitively in the EU, we are very pleased."

Costa expressed the view that the UK’s withdrawal without a deal "would be the worst way to solve the problem, for the EU, for the United Kingdom and for the world economy.

"Such a situation could not but impact on the whole world economy and would not only be a problem for the European economy," he warned.

The UK’s prime minister, Theresa May, on Monday announced that its parliament will be given the chance to choose between leaving the EU without a deal or seeking to postpone the date of the country’s departure if members reject the deal that the government lays before it in the coming weeks.