Women’s rights campaigners in Northern Ireland have vowed to join forces with pro-choice activists in the Irish Republic and MPs at Westminster to force the UK government to address the “denial of human rights” in 2019 by supporting moves to end the region’s abortion ban.

Activists urged Theresa May’s government not to sacrifice the rights and health of women at the altar of Brexit, and back potential legislation to decriminalise abortion in Northern Ireland.

The region has one of the strictest bans in the world, with women in almost every circumstance facing up to life in prison for a termination. The 1967 Abortion Act does not extend to Northern Ireland and an abortion cannot be performed legally even in cases of rape, incest and fatal foetal abnormalities.

But after the success of the repeal the eighth amendment campaign in helping to overturn the Republic of Ireland’s near-total ban on abortions in a landslide referendum victory, as well as polls showing strong support for a change north of the border, activists are motivated and energised in a manner not seen in decades, said Emma Campbell, who co-chairs the Alliance for Choice.

“The referendum in the south was really helpful, because you can basically no longer argue that the public don’t support a change in the law,” she said. “This has been a long fight with a lot of setbacks so we are cautiously optimistic, but I would say more optimistic than we’ve ever been.”

In the Irish Republic, the repeal campaign’s use of online platforms such as In Her Shoes to tell the stories of women forced to travel to other countries for an abortion also had a huge impact, said Campbell. “The public heard stories of travel that were no different to the stories here. It gave people courage … it has been such a huge open secret, but once you have broken the silence there is no putting the genie back in the bottle.”

In Northern Ireland, the Democratic Unionist party, which props up May’s government in Westminster, has refused to budge from its hardline support for the region’s Victorian-era abortion law. Sinn Féin, however, dramatically changed its stance after the referendum in the Irish Republic and backs liberalisation of the law.

Campaigners have the support of their counterparts in the Irish Republic who were ready to continue the struggle north of the border, said Ailbhe Smyth, a spokeswoman for the Coalition to Repeal the Eighth Amendment. “I think what’s maybe most important is we’ve actually managed it in the south,” she said. “If we had lost that referendum it would have set back that process, but winning it has given them great fire and determination.”

A number of elements have come together over the past couple of months to add fuel to that fire. In October polling by Amnesty International suggested 65% of adults in Northern Ireland thought abortion should not be a crime.

A supreme court ruling in June said that the region’s abortion laws were incompatible with human rights legislation. The decision has put further pressure on politicians to act even though the justices declined to issue a final ruling because the case brought before them did not involve an individual victim.

And with the Northern Ireland assembly not sitting since the collapse of the power-sharing government almost two years ago, campaigning MPs in Westminster sense they have an unprecedented opportunity. Last July more than 170 politicians from the UK and the Irish Republic signed a letter urging the UK government to reform Northern Ireland’s abortion laws.

The women and equalities select committee is carrying out an inquiry into those laws, and the minister for women and equalities, Penny Mordaunt, has told Northern Ireland’s politicians that if they did not liberalise the abortion law, Westminster would.

Thank you to all MPs who took part in todays debate.

With authority comes responsibility.

Message from NI Secretary of State today: NI should take that responsibility.

Message from the House of Commons: if you don't, we will.#trustwomen — Penny Mordaunt MP (@PennyMordaunt) June 5, 2018

Since the referendum, the Northern Ireland secretary, Karen Bradley, has also received letters from anti-abortion campaigners, including people born with serious conditions to maintain restrictions on abortion. One asked Bradley to confirm whether she was a Christian, writing: “It would seem that the most vulnerable in our society, the unborn child, is not permitted human rights.”

We can no longer stand by as women in Northern Ireland have their human rights breached Labour MP Diana Johnson

But a growing number of MPs support a change in the law, with a number taking direct action. A free vote on a 10-minute rule bill, put forward by Labour’s Diana Johnson, passed 208 votes to 123 with cross-party support, bolstering confidence among campaigners and supportive MPs even if the backbencher bill will not become law because the government has signalled that it will not give it parliamentary time.

“We can no longer stand by as women in Northern Ireland have their human rights breached,” Johnson told the Guardian. “It is quite clear that the Westminster parliament stands ready to deal with this.”

Many campaigners are now pinning their hopes on moves by her colleague Stella Creasy who, with Labour’s Conor McGinn, successfully tabled an amendment in October forcing Bradley “to issue guidance” on how officials can continue to enforce the region’s abortion law.

Stella Creasy: ‘Whatever deals the PM does with the DUP to stay in power we will not rest until abortion is free, safe, legal and local for every UK citizen.’ Photograph: Jack Taylor/Getty Images

Creasy plans to table an amendment to the government’s long-awaited domestic abuse bill.

“The lack of assembly cannot be used as an excuse not to act on this basic human rights issue,” said Creasy. “In 2019, we will be redoubling our fight against this injustice and seeking to amend legislation to decriminalise abortion across the UK including in Northern Ireland. Whatever deals the PM does with the DUP to stay in power we will not rest until abortion is free, safe, legal and local for every UK citizen.”

The situation for the women seeking an abortion was an ongoing tragedy, said Ruairi Rowan, an advocacy manager at the Family Planning Association in Northern Ireland. “People are still shocked when they find out that you can go to jail for buying abortion pills, that you can’t get an abortion if you are raped,.”

A woman faces prison after been embroiled in a legal battle for years after obtaining abortion pills for her underage daughter, who was in an abusive relationship.

A mural to Savita Halappanavar, who died of sepsis in 2012 after being denied an abortion in the Irish Republic during a protracted miscarriage. Photograph: Charles McQuillan/Getty Images

Women in Northern Ireland will be able to access services in the Irish Republic from this month. However, a three-day waiting period means women in desperate situations are likely to continue to travel to the rest of the UK where they now have access to free abortion services, said Rowan.

But campaigners are more determined than ever that 2019 will bring the change they argue Northern Ireland desperately needs, sai Goretti Horgan, an activist. Horgan said it took the death of Savita Halappanavar in 2012 after being denied an abortion during a protracted miscarriage to spark a mass movement for change south of the border, she said.

“Maybe the only way we can break the stalemate is to get tens of thousands on to the streets either here [in Northern Ireland] or london,” she said. “I just hope it won’t take another tragic death to make that happen.”