An attempt by MPs to liberalise abortion in Northern Ireland is "not workable" in its current form, Baroness Nuala O'Loan has said.
Last week, MPs voted to change Northern Ireland's abortion law and introduce same-sex marriage if devolution is not restored at Stormont by 21 October.
Baroness O'Loan said MPs had "hijacked" a Northern Ireland bill to push through changes without any consultation.
However, she withdrew an amendment in the House of Lords to reverse the vote.
After an emotive debate on Monday evening, Baroness O'Loan said she reserved the right to bring the amendment back before the House.
Earlier on Monday, she said the amendments approved by MPs were "not formulated" in a way that could become law.
"The clause which is currently in the bill does not work," the baroness told BBC News NI.
"It says the secretary of state must make regulations - the secretary of state can't."
The government has said the bill was not workable, she added, and it would be wrong of the government to "push it through in a situation where the people of Northern Ireland had no say".
She also pointed out that "100% of the Northern Ireland MPs who have taken their seat in Westminster voted against this".
The Democratic Unionist Party (DUP) opposed the amendment.
Abortion is only available in very limited circumstances in Northern Ireland and same-sex marriage remains illegal.
Amendments aimed at changing the law on both issues were tabled by Labour MPs Stella Creasy and Conor McGinn.
Baroness O'Loan is campaigning against liberalising abortion and has written a joint letter to the prime minister objecting to the MPs' actions.
The letter states that the amendments were supported only by MPs "who do not represent constituencies in Northern Ireland" and claims they have treated local voters "with contempt".
Co-authored by the Church of Ireland Archbishop Lord Eames, the letter was handed out at Catholic church services across Northern Ireland on Sunday.
The baroness, who is a former police ombudsman, said the amendments could damage efforts to restore Northern Ireland's locally-elected government, which collapsed in January 2017.
What happened in the House of Lords?
Peers clashed in the House of Lords on Monday night during an emotive debate on the proposed changes to abortion laws in Northern Ireland.
Baroness O'Loan withdrew her amendment and critiicsed the time set aside for the debate.
She said it was "terrible" that the future for unborn babies should rest on a few hours in the House of Lords.
Peers also debated plans to legalise same-sex marriage in Northern Ireland.
There were no votes taken on Monday night and the debate is expected to continue before the bill returns to the House of Commons on Thursday.
Earlier on Monday, the Labour MP Stella Creasy said the Commons "spoke clearly to say we wouldn't accept the rights of women in Northern Ireland being ignored any longer".
"There's increasingly worrying rumours the government will back wrecking amendments or even pull the bill all together rather than act to ensure everyone in the UK has equal access to safe, legal and local abortion rights," she said.
"Any delay in this legislation, any attempts to derail it or deny it, must be called out and resisted and called out for what they are - an attempt by the DUP to hold us all to ransom."
The year before the Northern Ireland Assembly collapsed, MLAs voted against liberalising abortion even in some of the most difficult circumstances.
Last Wednesday in the House of Lords, the Northern Ireland (Executive Formation) Bill was moved on behalf of the government by parliamentary under-secretary of state at the Northern Ireland Office, Lord Duncan of Springbank.
He told peers that the bill had been amended in the Commons to "oblige the government to introduce regulations to provide for same-sex marriage and abortion".