Conservative MPs have warned new UK government powers to force Northern Ireland to expand abortion services are "putting the Union at risk".
The legislation, published this week, allows Northern Ireland secretary Brandon Lewis to intervene and ensure safe abortions to meet United Nations rights obligations.
Significant changes to Northern Ireland's abortion laws, agreed in 2019, came into force last March, allowing terminations in all circumstances in the first 12 weeks of pregnancy, and in some cases after that.
But Mr Lewis said services have not yet been commissioned, which "leaves many women and girls in vulnerable positions".
However, several Tory MPs were unhappy with the move, with former minister Sir John Hayes saying it was "unjust" while Scott Benton described the new regulations as "a democratic and constitutional assault on Northern Ireland".
Northern Ireland First Minister Arlene Foster called on Boris Johnson's government to "back off" in its attempts to bypass the devolved government.
"This is a hugely complex, controversial, legally challenging issue for the [Northern Ireland] executive," she told a press briefing.
"But let us be very clear, it is for the executive. It is not for Brandon Lewis.
"He should back off."
Mr Lewis argued that Northern Ireland is violating its human rights obligations but Sir John said that was "simply untrue".
The Northern Ireland secretary added: "I would just say to (Sir John) that this is a matter of domestic law, I've been clear about this, it's about the legal obligation that's been taken forward from this house in 2019."
Conservative MP Sir Edward Leigh accused the government of using the fact the Northern Ireland Assembly was not sitting "to impose its views on Northern Ireland".
However, MP for North Down Stephen Farry said most women in Northern Ireland supported the government stepping in.
"I would stress that there is large-scale support in Northern Ireland for these actions.
"It is simply not tenable to have a right on paper but not in practice and for different reproductive rights to exist across the UK."
Mr Lewis added that he had spoken to "many" women and healthcare professionals in Northern Ireland whose experiences are "truly harrowing", with some attempting suicide after their flights to England to have an abortion were cancelled.
"Too many women and girls are still having to travel to other parts of the United Kingdom, to mainland Great Britain, to access this care," he said.
"One story was of a much-wanted pregnancy where sadly doctors informed the mother that the baby would not survive outside of the womb. This woman had to travel to London without her network of family support in order to access healthcare.
"She described to me a harrowing ordeal. Unable to travel back on a flight to her home because of complications and bleeding, stranded in London alone and grieving and in pain."