Taoiseach Leo Varadkar has been sent a letter signed by 1,000 nationalists urging him to defend the rights of Irish citizens north of the border amid uncertainty caused by Brexit and Stormont's political crisis.

The letter to Mr Varadkar has been signed by actors, academics, professional athletes, entrepreneurs, lawyers, teachers, doctors and a range of other figures from within civic nationalism.

The signatories include Republic of Ireland international footballer James McClean, actors Adrian Dunbar and Ciaran McMenamin, film director Jim Sheridan and folk musicians Tommy Sands and Colm Sands.

Two similar letters have been written to the Taoiseach in the last 12 months, one from a number of nationalists based in Northern Ireland and one from nationalists residing south of the border.

The latest, which was sent on Friday and published in the Irish News today as a two-page advert, has the largest number of signatures and is an all-island endeavour.

The letter welcomes Mr Varadkar's pledge to defend the interests of Irish citizens living in Northern Ireland through the Brexit process but blames the Stormont power-sharing impasse, which has seen the absence of devolved government for almost two years, for "denying" certain "rights" to people north of the border.

It highlights Democratic Unionist opposition to same-sex marriage and an Irish Language Act as two key issues of concern.

The letter adds: "As you know these rights are now taken for granted by citizens in other parts of these islands.

"The British Conservative government has rendered itself unable to effect any progress on these rights issues due to its dependence on the DUP.

"Brexit threatens to deepen the rights crisis and there is a real danger of serious erosion of current guarantees."

On Brexit, the letter raises concerns about access to free healthcare in EU countries; a potential hike to the cost of attending university in the Irish Republic; and the fact Irish citizens living in Northern Ireland will no longer be represented in the European Parliament.

The letter continues: "There is a very real potential that partition could be reinforced, and our country and our people further divided.

"This is a source of grave concern to all of us.

"We, as Irish citizens, urge you to adhere to your commitment that we would 'never again be left behind by an Irish Government' and to redouble your efforts, and the efforts of your government, to ensure that our rights are protected."

Plans for the latest letter were first reported last month by the Co Fermanagh-based newspaper, the Impartial Reporter, which interviewed Enniskillen-born actor Mr McMenamin about his rationale for signing it.

He told the paper he was concerned that the imposition of a hard border post-Brexit could spark violence.

"Brexit and a border causing violence is a possibility and one that should never be overlooked but Brexit and a border causing economic chaos is a fact and one that is being totally overlooked by the DUP," he said.

"It won't make anyone more British, it will just make everyone poorer."

Belfast lawyer Niall Murphy, who has been involved in compiling the letter, said every section of nationalist civic life was represented among the signatories.

"That this letter is signed by over a thousand leaders from the nationalist community is a testament to an evolving earthquake in terms of an awakening of nationalist confidence," he said.

"The 1,000 names are symbolic, the letter is not a petition, but a representative sample of the views of hundreds of thousands of people across the north and indeed across the entire island."