Sinn Fein Leader Mary Lou McDonald arrives for a meeting with European Union Chief Brexit Negotiator Michel Barnier at the E.U. Commission headquarters in Brussels, Belgium, January 9, 2019. REUTERS/Francois Lenoir

BELFAST (Reuters) - Irish nationalists warned British Prime Minister Theresa May on Wednesday that if she allowed a disorderly no-deal Brexit then there would have to be a referendum on Irish unity.

“We have said to her, in the event of a crash, in the event of a Tory crash, that she must as a democrat return to the Good Friday Agreement, and she must begin preparation for a referendum on Irish unity,” Sinn Fein leader Mary Lou McDonald said.

“If British politics cannot accept the specific needs of this country, of the north of Ireland, if British politics is incapable of acknowledging and upholding the Good Friday Agreement and preventing a hardening of the border, then the only last option – the backstop of last resort – is a referendum on Irish unity,” she said.