A high-profile appeal by the Christian owners of a Belfast bakery who were found to have discriminated against a gay customer has been dramatically halted to facilitate an intervention by Northern Ireland's top legal adviser.   

Attorney General John Larkin QC has made a last-minute request to make representation in the case about any potential conflict between the region's equality legislation and European human rights laws.

The McArthur family's refusal to bake the customer's order for a cake bearing a pro-gay marriage slogan was ruled unlawful last year.

Northern Ireland's Lord Chief Justice Sir Declan Morgan said: "It is most unfortunate this issue has arisen only two days before this hearing.

"Although we have all tried to see if we could proceed with the case given the amount of work that has been done.

"It seems to us that it is simply not possible to do that without running into some risk of fairness in the hearing.

"We are not going to proceed with the hearing today."

Arriving at Belfast High Court for the start of the appeal, Daniel McArthur, 26, insisted the original ruling was wrong.

"We took issue with the message on the cake and not the customer, and as a family we do believe we should retain the freedom to decline business that would force us to promote a cause with which we profoundly disagree," he said.

"As Christians we cannot simply switch off our faith when we enter the workplace on a Monday morning.

"To be a Christian at all is to strive to live for Christ in every corner of our lives."

Gay rights activist Gareth Lee, a member of LGBT advocacy group Queer Space, had wanted a cake featuring Sesame Street puppets Bert and Ernie with the slogan Support Gay Marriage for a private function marking International Day Against Homophobia in May 2014.

He paid in full when placing the order at Ashers' Belfast branch, but two days later the company phoned to say it could not be processed.

The high-profile case was heard over three days last March.

Delivering her reserved judgment two months later, District Judge Isobel Brownlie found Ashers directly discriminated against Mr Lee who had been treated "less favourably", contrary to the law.

Ordering the bakers to pay agreed damages of £500, the judge said religious beliefs could not dictate the law.

The Northern Ireland Equality Commission, which monitors compliance with the region's anti-discrimination laws, took the landmark legal action on behalf of Mr Lee.

Mr McArthur said the bakery treated Mr Lee like any other customer.

"We were simply unwilling to endorse a campaign for a new law that so clearly goes against what the Bible says about marriage. And for that we were punished.

"Christians are law-abiding citizens and we expect the law to protect us as much as anyone else.

"We hope that the judicial system will now make the correct decision and protect our freedom to carry out our work without being forced to violate our consciences.

"As a family we have found the whole legal process very difficult.

Daniel McArthur and his wife Amy McArthur arrive at court

"We would rather not have to be here today. But we knew that we had to appeal, not only on our own behalf, but on behalf of other family businesses who could be forced to endorse or promote views with which they profoundly disagree."

He added: "We appeal to those who would condemn us for our actions to consider what they would have done if they were required by law to use their creative abilities to help promote a cause which went against their strongest convictions."

Mr Lee has not spoken publicly about the case outside of the courtroom.

In evidence in the original case, he claimed the company's refusal to make the cake left him feeling like a "lesser person".

The publicly funded Equality Commission initially asked the bakery in Royal Avenue to acknowledge it had breached legislation and offer "modest" damages, but proceeded with the court challenge when the firm refused.

Ashers, which employs 80 staff in nine branches and delivers across the UK and Ireland, has been supported by the Christian Institute, which organised public meetings and garnered financial backing.

The issue of gay marriage has split public opinion in Northern Ireland.

In 2005, the region became the first in the UK to allow same-sex civil partnerships, but the devolved Stormont Assembly has repeatedly refused to change the law around marriage.

Following last May's referendum in the Republic of Ireland, it is now the only part of the UK or Ireland to deny civil marriage to same-sex couples.

Two same-sex couples are seeking to challenge the ban through a judicial review in the courts.