The article 50 process to begin the United Kingdom's formal withdrawal from the European Union can be activated without the consent of the people of Northern Ireland, or separate parliamentary approval, a Belfast High Court judge ruled today.

On judicial reviews brought by victims' campaigner Raymond McCord and a group of MLAs from Sinn Féin, the SDLP, Alliance and the Green Party, Mr Justice Paul Maguire ruled also that there was nothing in the 1998 Good Friday peace agreement to prevent the Government triggering article 50.

The claimants argued that the effect of the Northern Ireland Act 1998 was that the prerogative power had been displaced and an Act of Parliament was required to trigger article 50. Mr McCord further argued that the Good Friday agreement meant that Westminster had given sovereignty over Northern Ireland to its people.

The judge ruled that parliamentary approval was not necessary as "the actual notification does not, in itself, alter the law of the UK"; it was only "the beginning of a process which ultimately will probably lead to changes in UK law".

In his judgment, he stated: "On the day after the notice has been given, the law will in fact be the same as it was on the day before it was given. The rights of individual citizens will not have changed – though it is, of course, true that in due course the body of EU law as it applies in the UK will, very likely, become the subject of change.

"But at the point when this occurs the process necessarily will be one controlled by parliamentary legislation, as this is the mechanism for changing law in the UK."

However he added that his decision was "without prejudice to the issues which have been stayed and which are under consideration in the English courts".

A ruling is awaited in separate proceedings before the High Court in London. That action is expected to be apealed to the UK Supreme Court, and a solicitor for the claimants in the present case said that case was also likely to be appealed.

Welcoming the ruling, a spokesman for the UK Government said: "As we have always made clear, we stand by our commitments under the Belfast Agreement and the outcome of the EU referendum doesn't change this."

Click here to view the judgment.