Theresa May to trigger Brexit negotiations on March 29

The Union Jack (bottom) and the European Union flag are seen flying, at the border of Gibraltar with Spain, in the British overseas territory of Gibraltar, historically claimed by Spain, June 27, 2016, after Britain voted to leave the European Union in the EU Brexit referendum. REUTERS/Jon Nazca/Files

British Prime Minister Theresa May will begin the official process of the UK's exit from the European Union (EU) on March 29, her spokesperson announced today.

The UK’s ambassador to the EU, Sir Tim Barrow, formally informed EU Council president Donald Tusk of the date this morning.

"We said it would be by the end of March and thought it would be helpful to say when it will happen. We want negotiations to start promptly. We expect it will be a two-year process and we are confident that is what we will achieve. So Britain will exit the EU on 29 March 2019," the Downing Street spokesperson said.

The UK expects to receive a response to Barrow’s notification from the EU Council within 48 hours, he added.

The move comes nine months after Britain voted 51.9 per cent to 48.1 per cent in favour of Brexit in a referendum on June 23, 2016.

Talks on the terms of the UK’s departure and future relations with the EU are not possible until the UK formally notifies the EU it is leaving.

May has already announced that she will make a statement to the House of Commons shortly after invoking Article 50 of the Lisbon Treaty.

If all goes according to the two year negotiations set out in the official timetable, Brexit should happen in March 2019.