The European Union will intensify its preparations for a scenario in which Britain leaves the bloc without a withdrawal agreement, the bloc's chief executive said tonight.

"The risk of a disorderly withdrawal of the United Kingdom has increased with this evening's vote," Commission President Jean-Claude Juncker said in a statement following the British parliament's rejection of a Brexit deal with the EU.

"While we do not want this to happen, the European Commission will continue its contingency work to help ensure the EU is fully prepared," he said.

Belgium's Prime Minister Charles Michel said on Twitter his country was also stepping up its planning for a Brexit no-deal.

Donald Tusk, meanwhile, urged British politicians to rethink their Brexit strategy after parliament rejected the planned withdrawal agreement, implying London should reconsider leaving the union.

"If a deal is impossible, and no one wants no deal, then who will finally have the courage to say what the only positive solution is?" Mr Tusk, the president of the European Council, tweeted.

A spokesman for Mr Tusk said: "We regret the outcome of the vote, and urge the UK Government to clarify its intentions with respect to its next steps as soon as possible.

"The EU27 will remain united and responsible as we have been throughout the entire process and will seek to reduce the damage caused by Brexit.

"We will continue our preparations for all outcomes, including a no-deal scenario. The risk of a disorderly exit has increased with this vote and, while we do not want this to happen, we will be prepared for it.

"We will continue the EU´s process of ratification of the agreement reached with the UK Government. This agreement is and remains the best and only way to ensure an orderly withdrawal of the United Kingdom from the European Union."