The head of the European Union's executive, Jean-Claude Juncker, on Sunday urged the UK parliament to ratify the Brexit deal the bloc sealed with British Prime Minister Theresa May.

"This is the best deal possible. I'm inviting those who have to ratify this deal in the House of Commons to take this into consideration. This is the best deal for the UK, the best deal for Europe, this is the only deal possible," Juncker said.