Prime Minister Theresa May has kicked off the two-year process of Britain's withdrawal from the European Union in what she said was "an historic moment from which there can be no turning back".

Minutes after a letter informing the European Council of the UK's intention to leave, Mrs May told the House of Commons that the Government was acting on "the democratic will of the British people" expressed in last year's referendum vote for Brexit.

The historic declaration under Article 50 of the EU treaties - signed by Mrs May on Tuesday - was personally hand-delivered to EC president Donald Tusk in Brussels by the UK's permanent representative to the EU, Sir Tim Barrow.

Describing EU withdrawal as one of the "great turning points in our national story", Mrs May told MPs: "Today, the Government acts on the democratic will of the British people and it acts too on the clear and convincing position of this House."

Mrs May said: "The Article 50 process is now under way and, in accordance with the wishes of the British people, the United Kingdom is leaving the European Union.

"This is an historic moment from which there can be no turning back. Britain is leaving the European Union.

"We are going to make our own decisions and our own laws, we are going to take control of the things that matter most to us, and we are going to take this opportunity to build a stronger, fairer Britain - a country that our children and grandchildren are proud to call home.

"That is our ambition and our opportunity."