British PM Theresa May signs Brexit letter invoking Article 50

British Prime Minister Theresa May signed a letter on Tuesday to European Council President Donald Tusk notifying the European Union of Britain's intention to leave the bloc, a photograph seen by Reuters showed.

The letter is due to be delivered by hand to Tusk in Brussels on Wednesday by Tim Barrow, Britain's permanent representative to the EU. May will also notify parliament about the letter.

Anti-Brexit demonstrators protest outside the Supreme court building in London on the first day of a four-day hearing on December 5, 2016. The government of Prime Minister Theresa May will today seek to overturn a ruling that it must obtain parliamentary approval before triggering Brexit, in a highly-charged case in Britain's highest court. DANIEL LEAL-OLIVAS / AFP