British prime minister Theresa May has been put on notice that she faces a legal challenge from prominent Northern Ireland politicians and interest groups over Brexit.

Mrs May will meet First Minister Arlene Foster and Deputy First Minister Martin McGuinness in Stormont today on her first visit to Northern Ireland as prime minister.

Ahead of the visit, however, senior politicians, who include the SDLP and Alliance leaders and a former Sinn Féin minister, have demanded that Mrs May ensure that the Belfast Agreement and the peace process are legally protected before there is any legal move by the UK to leave the EU.

EU law

They said they would seek a judicial review if Mrs May “fails to commit to comply with the UK’s constitutional and legal obligations in deciding whether and when to trigger article 50”, the mechanism that must be activated to take the UK out of the EU.

“These obligations include safeguarding the unique requirements of Northern Ireland constitutional law and statute, in particular the statutory recognition of the Belfast-Good Friday Agreement, and satisfying the requirements of EU law incorporated into the law of Northern Ireland by the European Communities Act 1972,” they said.

The group, which includes former Sinn Féin education minister John O'Dowd, SDLP leader Colum Eastwood, Alliance leader David Ford and Green Party leader Steven Agnew, have asked the prime minister and new northern secretary James Brokenshire to respond within two weeks.

Before flying to Belfast, Mrs May said: "I have been clear that we will make a success of the UK's departure from the European Union. That means it must work for Northern Ireland too, including in relation to the Border. We will engage with all of Northern Ireland's parties as we prepare for that negotiation."

Peaceful

The group, as part of its legal argument, stated the British government must accord “adequate weight” to the fact that a majority of people in Northern Ireland – 56 per cent – voted to remain in the EU.

It also demanded that in deciding when article 50 was activated, the British government must protect “the progress made towards a peaceful society”.

The group’s legal representatives, Belfast firm Jones Cassidy Brett, said that the British government could only trigger article 50 “after properly taking into account all relevant alternatives to exiting the EU and not giving undue weight to the results only of this referendum”.