Theresa May has shown "disdain" for Northern Ireland by calling a snap general election amid intense efforts to restore powersharing, a nationalist leader has said.
The third electoral contest in the region in just over a year beckons against a backdrop of political instability.
Another Stormont ballot cannot be ruled out if a deal forging a devolved administration is not struck within days.
Social Democratic and Labour Party (SDLP) chief Colum Eastwood said: "It tells you all you need to know about Theresa May that she would call a snap Westminster election in the middle of intense efforts to restore powersharing government to Northern Ireland.
It shows you how much .@TheresaMayPM thinks/cares about our peace process that she'd call an election in the middle of talks.
— Colum Eastwood (@columeastwood) April 18, 2017
"From the beginning of her tenure as British Prime Minister she has shown very little but disinterest and disdain for this place.
"As Theresa May seeks a mandate for a hard Brexit from an English electorate, people here have an opportunity to unite behind parties which have defended their will and sought to protect our values."
Northern Ireland voted Remain by a majority of 56% to 44%, although some large mainly unionist areas opted for an exit.
Mr Eastwood added: "As Theresa May seeks a mandate for a hard Brexit from an English electorate, people here have an opportunity to unite behind parties which have defended their will and sought to protect our values."
Northern Ireland held Stormont polls twice in under a year as powersharing between the two biggest parties, the DUP and Sinn Fein, faltered.
So Ms May has called a British General Election. Sinn Féin is up 4 that! Another chance 2 vote against Brexit & 4 progress.
— Gerry Adams (@GerryAdamsSF) April 18, 2017
In March a Sinn Fein surge saw the republican party under the leadership of Michelle O'Neill at Stormont emerge with just one seat less than the DUP.
Political rescue talks to restore devolved government are due to conclude by early next month.
If they are unsuccessful, Northern Ireland Secretary James Brokenshire has to decide whether to call fresh Assembly elections or impose direct rule by ministers from London.
In the past electoral contests have polarised the fractious parties.
Minister @CharlieFlanagan on Prime Minister May's announcement today. Full text here: https://t.co/dRUvE5WZc9 pic.twitter.com/a5zbW1Fnq5
— IrishForeignMinistry (@dfatirl) April 18, 2017
DUP leader Arlene Foster said: "The forthcoming election will be an opportunity for unionists to unite around a strong DUP that will advocate for them in Parliament."
Mrs O'Neill said the Tory Party and its polices have been rejected by the people in the north in the past and will be again in this election.
"Sinn Fein is ready to contest this election and it will be an opportunity for voters to oppose Brexit and reject Tory cuts and austerity."