THERESA May is under growing pressure to reform Northern Ireland’s strict abortion law after a cross-party group of MPs threatened to repeal the 150-year-old statute behind it.

Labour backbencher Stella Creasy said axing parts of the Offences against the Persons Act of 1861 would force a new law to be drawn up in Northern Ireland to fill the gap.

Pressure for reform in the North has been growing since last month’s 2-to-1 referendum vote to end the constitutional ban on abortion in the Irish republic.

But DUP leader Arlene Foster, whose party props up the UK government, fiercely opposes any change to the Northern Ireland ban on abortion in all but exceptional circumstances.

Ms Foster, who will join an Orange Walk in Fife this month, said on Sunday that even Sinn Fein supporters and Irish nationalists would vote for her party because of its pro-life position.

Sinn Fein will consider whether to back abortion up to 12 weeks at its conference this month.

Downing Street has said abortion remains “an issue for Northern Ireland”, however the lack of an executive there for more than a year has led to calls for Westminster to step in.

The 1967 Abortion Act created exemptions from the 1861 Act in England and Wales.

Ms Creasy said: “The Offences against the Person Act passed in 1861 puts abortion in the same category as rape, child stealing and using gunpowder to blow people up.

“What that means is that right now in Northern Ireland, where there are no exemptions to this law, if you are raped and you become pregnant as a result of that rape, and you seek a termination, you would face a longer prison sentence than the person who attacked you.

“This is about repealing a piece of UK legislation that stops people in Northern Ireland having medical rather than criminal laws about abortion."

Ms Foster said voters felt the DUP was now “the only party that supports the unborn”, and that people “feel so very strongly about this issue that they will cast their vote on that basis".

She told Sky News: “I have had emails from Nationalists and Republicans in Northern Ireland not quite believing what is going on and saying they will be voting for the DUP because they believe we are the only party that supports the unborn."