BELFAST : Northern Ireland 's High Court on Friday rejected a legal challenge to Brexit , the first judicial ruling on the issue in the UK which is being closely watched by politicians and the financial markets.

The claims rested on aspects of Northern Ireland 's 1998 Good Friday peace accords, which largely ended three decades of sectarian conflict. "In respect of all issues, the court dismissed the applications," judge Paul Maguire said. One of the parties bringing the challenge said immediately afterwards that there would be an appeal to the Supreme Court in London, the UK's highest court . A cross-party group of politicians claimed Northern Ireland should have a veto on leaving the European Union, and the Northern Irish Assembly should have a say on whether to trigger exit negotiations with Brussels. The claim was brought alongside a linked challenge on the impact of Brexit on the Northern Irish peace process, brought by veteran victims' rights campaigner Raymond McCord.

The claims rested on assumptions spiralling from the Good Friday Agreement that Northern Ireland 's constitutional arrangements could only be changed with the consent of its residents.

England and Wales, Scotland and Northern Ireland have separate legal systems within the United Kingdom.

Other legal challenges are under way elsewhere in England, making the ruling at the High Court in Belfast an important first test.

In the June 23 referendum on EU membership, 52 percent voted for Britain to leave the European Union. Within Northern Ireland , 56 percent voted to stay.

Maguire said it was "difficult to see how the court can overlook the importance of the terms in which the 1998 Act are cast or to deviate from what to date has been plain, namely that the United Kingdom parliament has retained to itself the ability to legislate for Northern Ireland without the need to resort to any special procedure."

British Prime Minister Theresa May has said she will trigger Article 50, the formal procedure for leaving the EU which takes up to two years, between the new year and the end of March.

The verdict comes after three days of hearings earlier this month. "While the wind of change may be about to blow, the precise direction in which it will blow cannot yet be determined so there is a level of uncertainty," Maguire said.

Outside the court , McCord said he was "looking forward to seeing a bit more of London" in taking his challenge to the Supreme Court . "We will certainly be appealing - in my view the judge took a safe decision but he left it open for us to appeal and we will," he said.

McCord's lawyer Ciaran O'Hare added: "We didn't expect to win today because this was always going to an appeal. "We are disappointed but today was a skirmish, the main battle is yet to come."

Former Northern Ireland justice minister David Ford, who was involved in the politicians' legal challenge , said they would be mulling an appeal in the coming days. "We are disappointed but it remains our duty to protect the people of Northern Ireland ," he said.