But until decisions are made, the EU is continuing to prepare for a vote without taking the United Kingdom into account, he added.

Valente explained that on Tuesday morning the UK did not ask to to revoke Article 50 - the legal process by which Britain is leaving the EU - or to be granted an extension.

Therefore the current scenario was that the United Kingdom would not participate in European elections, he pointed out.

However, just 10 days before the UK is scheduled to leave the European Union, on 29 March, and with little more time to get its withdrawal agreement approved by the British parliament, it is likely the country will ask for Brexit to be delayed, he said.

Valente said the delay could be of "two, three, nine, twelve" months or more.

He said the main concern regarding extending Article 50 was the European elections, pointing out that if the extension request goes beyond 2 July, the United Kingdom will have to take part in the May 23-26 votes.

On Monday, European sources cited in British media warned that prolonging Brexit beyond 23 May, when the elections begin to take place in some member states, would mean European elections would have to take place in the UK.