Sinn Féin leader Mary Lou McDonald has doubled down on her Irish reunification U-turn and said a unity referendum is now at the centre of political discussion.

The comments come a week after Ms McDonald said a poll on Irish unity should not be held while uncertainty around Brexit remains.

Now Ms McDonald has said: "It is not a question of if a unity referendum will happen but a question of when."

Ms McDonald made the remarks during her keynote speech at the 37th annual National Hunger Strike Commemoration in Castlewellan, Co Down.

She added that the process of building a new and united Ireland must include unionists, and the Government has a responsibility to lead the discussion.

"The need for a referendum to end partition is writ large and the time for a unity referendum is drawing near.

"Political leaders must begin practical preparations for a new, inclusive Ireland beyond partition.

"The Irish Government in particular has a responsibility to lead an informed, reasoned and respectful public dialogue on this issue.

"As Britain turns away from Europe, the appeal of being part of a new and outward-looking Ireland will, I believe, prove ever more attractive to some within the unionist community.

"British identity can and must be accommodated in a united Ireland and I believe nationalist Ireland is open to constitutional and political safeguards to ensure this."

The Sinn Féin leader added that the party is committed to re-establishing the Executive and Assembly in Northern Ireland.

"The Irish and British Governments have said there will be a new round of talks in the autumn. That is welcome.

"However basic rights, respect and equality cannot be disregarded, they are not bargaining chips.

"They are for all in society.

"Marriage equality, the right to inquests and language rights are for everyone.

"The way to unlock the political process is to make clear that rights enjoyed in the rest of Ireland and across Britain will be implemented in the north."

Ms McDonald added there are more Republicans across Ireland now than at any time since partition.

"The tide of history is with those who seek a united Ireland.

"It is increasingly clear that the partition of Ireland is an obstacle to building a modern, open and forward-looking society.

"Brexit and the prospect of a hard border are further exposing the fact that a divided Ireland does not serve the needs of our people."

The sudden U-turn in party policy has garnered much criticism from Sinn Féin's political opponents this week who say it raises questions over Ms McDonald's leadership.