THE north's economy and farming industry are too closely linked to the EU to risk leaving it, British Prime Minister David Cameron warned.
Mr Cameron is to visit the north today as part of his EU referendum campaign.
His Tory rival, London mayor Boris Johnson, who favours a withdrawal, is expected to visit on Monday.
Speaking ahead of his trip, Mr Cameron warned the north's voters of the potential economic impact of Brexit.
Mr Cameron said the north is "better off" in a reformed EU.
"More than 60 per cent of Northern Ireland's exports go to the EU, and around 40 per cent of its investment comes from the EU. Putting that at risk is a leap in the dark," he said.
"It's vital that the voices of Northern Ireland's farmers are heard in this debate.
"They want security and certainty. I've never argued the EU is perfect, but I believe a reformed Europe gives them access to a huge single market and an income that helps them keep food prices low for families.
"Those who want the UK to leave the EU need to give answers on their alternatives."
Treasury figures put the number of jobs in Northern Ireland linked to EU trade at 50,000, with exports up over 50 per cent in real terms since 1998.
The north's political parties are split on the issue, with the DUP backing an exit and Sinn Féin, the SDLP and Alliance in favour of remaining in the bloc.
The Ulster Unionists have delayed making a public announcement on their position until they have an internal debate on Mr Cameron's EU reform deal.
However, UUP leader Mike Nesbitt has already made several pro-EU remarks in recent days.
Secretary of State Theresa Villiers is one of five cabinet ministers who have broken ranks to campaign for the UK to end ties with Brussels.
Her stance prompted criticism from nationalist politicians.
However, Mr Cameron pledged his support, telling the Commons Ms Villiers does an "excellent job".
