LONDON (REUTERS) - Britain's Attorney General Jeremy Wright said the government's appeal to the UK Supreme Court over who has the right to trigger the formal divorce process from the European Union goes to the heart of the British constitution.

"It raises issues going to the very heart of our constitutional settlement," Wright told the court.

Wright's comment came at the start of a four-day appeal by the government against a High Court ruling last month that it has to seek parliamentary assent before triggering Article 50 of the EU's Lisbon Treaty.