UK PM May Signs Article 50 Letter To Trigger Brexit

UK Prime Minister Theresa May signed a letter late Tuesday that notifies the European Union of her government invoking the Article 50 of the Lisbon Treaty, which will trigger the formal 'Brexit' process.

Britain's Ambassador to the EU Tim Barrow will deliver the letter to the European Council President Donald Tusk in Brussels on Wednesday.

May is set to address the British parliament later on Wednesday, while Tusk is scheduled to make a press statement in Brussels on the UK notification around 13.45 local time.

The uncertain negotiation process under Article 50 must be completed in two years from the date of triggering.

On Tuesday, May spoke over the phone with the German Chancellor Angela Merkel, Tusk and the European Commission President Jean-Claude Juncker to update them of the proceedings.

"In separate calls, they agreed that a strong EU was in everyone's interests and that the UK would remain a close and committed ally," a Downing Street spokesperson said.

"They also agreed on the importance of entering into negotiations in a constructive and positive spirit, and of ensuring a smooth and orderly exit process," spokesperson added.

Juncker called the phone call with May "good and constructive".

Elsewhere, EU's Chief Brexit Negotiator Michael Barnier said the event made EU citizens worry about their future in EU27 and the UK.

"EU will be firm on their rights," Barnier said on the short messaging service Twitter.