Pro-life campaigners have revealed plans to open an office in Belfast.
The Society for the Protection of Unborn Children (Spuc), which opposes any attempts to legalise abortion in Northern Ireland, said it is expanding its operations.
The campaign group has had a presence here for more than 35 years.
Political officer Liam Gibson said: "Our decision to expand our activities in Northern Ireland comes at a time when the country is coming under pressure on abortion like never before.
"Along with Malta, Northern Ireland is now the only place in Europe which recognises the right to life before birth. Yet the international abortion lobby is prepared to work night and day to stamp out the last areas of resistance to the killing of unborn children."
In May the Republic voted to repeal part of its constitution that outlawed abortion.
It has left this the only part of the UK or Ireland where abortion is illegal unless there is a serious risk to a woman's life or health. The 1967 Abortion Act does not extend to Northern Ireland.
Mr Gibson said: "The result of the recent referendum in the Republic of Ireland has left Northern Ireland isolated and fuelled the clamour for change from the pro-abortion lobby here.
"We are facing a twin-pronged attack from pro-abortionists in Westminster who are seeking to override devolution and impose decriminalisation on Northern Ireland through the House of Commons while the Stormont Assembly - which has legal authority over abortion law - is in limbo.
"At the same time the Dublin government, which denied people north of the border a vote in the referendum, says it will be happy to kill our children when its abortion law comes into effect in the Republic."
John Deighan, deputy chief executive of Spuc, said: "This is a massively important time for the pro-life movement as our fundamental beliefs and those of many people in Northern Ireland are facing an unprecedented challenge from those who think nothing of the rights of the voiceless unborn children nor the health of their mothers."
Reacting to the news, pro-choice activist Clare Bailey of the Green Party said she was very conscious that anti-abortion campaigners were concentrating their activity on Northern Ireland in the wake of the referendum in the Republic, and renewed her call for Westminster to legislate for abortion law reform in Stormont's absence.