LONDON • A Northern Irish judge rejected a pair of challenges to the Brexit process, removing at least one obstacle to British Prime Minister Theresa May's plan to begin severing ties with the European Union by the end of March.

Justice Paul Maguire said yesterday that it was beyond the power of the Belfast court to interfere with how the government triggers Article 50, the notice of departure from the EU. He dismissed claims related to lawmakers' votes and the Good Friday Peace accord in Ireland.

"The actual notification does not, in itself, alter the law of the UK," the judge noted in his decision. "Rather, it is the beginning of a process."

When laws do have to be changed, Parliament will necessarily be involved, he said.

There are fears that Brexit could undermine a 1998 peace deal, the Good Friday Agreement, which ended three decades of bloodshed in the province, and could lead to the reintroduction of unpopular controls on the border with the Republic of Ireland, an EU member.

Activist Raymond McCord and a group of politicians bringing the Belfast lawsuit alleged that it would be illegal for Mrs May to unilaterally start the exit without lawmakers weighing in. In addition, they argued that the shared border with Ireland and EU funds provided to victims of terrorist violence complicate the decision to exit.

The decision in Belfast comes as a panel of three senior judges in London considers a similar case demanding a parliamentary vote before Mrs May invokes Article 50 of the Lisbon Treaty. It is likely both of the cases will be swiftly appealed to the UK Supreme Court for another hearing.

Investors have looked to the lawsuits to delay the move towards Brexit amid concerns that the Prime Minister is prioritising immigration controls over safeguards for trade and banking. The June 23 referendum vote has caused the pound to lose 18 per cent of its value - more than any other major currency - over fears that whatever deal emerges from negotiations between Mrs May and the EU will leave the country worse off.

"We welcome the court's judgment this morning," Mrs May's spokesman, Mr Greg Swift, told reporters in London yesterday. "We can proceed to trigger Article 50 as planned."

Northern Irish residents - like those in Scotland - voted to remain in the EU during the non-binding referendum, which the "Leave" campaign won by 52 per cent to 48 per cent across Britain.

The ruling may have implications for Scotland, whose government argues it should have a say on Brexit because it too voted to remain in the EU.

Mrs May, originally a "Remain" supporter, has pledged to follow through on the voters' will, and said that she will reach the best agreement possible to restrict immigration to Britain while keeping close economic ties, a goal that EU officials have said will be difficult.

BLOOMBERG, REUTERS