The 'gay cake' case has been dramatically adjourned following a last minute intervention from Northern Ireland's Attorney General.

Ashers Bakery, owned by the McArthur family, was appealing a ruling after they refused to produce a cake with a "support gay marriage" slogan. They were fined £500 after a Belfast court ruled they had discriminated on the grounds of sexual orientation.

However their appeal was postponed after a late intervention from John Larkin QC, Attorney General in Northern Ireland, which raised a potential conflict between the region's equality legislation (which is not the same as the 2010 Equalities Act) and European human rights laws.

The lateness of the representation was "most unfortunate" said Northern Ireland's Lord Chief Justice Sir Declan Morgan, who was presiding over the appeal.

"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."

The hearing will be postponed until May and it is understood the questions surround the legality of Northern Ireland's sexual orientation regulations. It currently prohibits the refusal of services on the grounds of religion, race or sexual orientation.

The Court of Appeal will meet in March, ahead of the hearing in May, to hear the legal arguments on the compatibility of Northern Ireland law with European human rights law.

The court will also decide if any conflict raises a devolution point which would open up the possibility of Attorney General John Larkin QC to become involved.

After the announcement, Daniel McArthur, general manager of Ashers Bakery, said: "We were fully prepared for the hearing to go ahead and arrived this morning in full expectation it would do so. However, developments have taken place which are clearly out of our control due to the decision by the Attorney General to intervene. Clearly, our case raises matters of crucial importance if he has taken a decision to become involved.

"We have every confidence in our legal team and the arguments which were to be put forward and we had also clearly placed our trust, as always, in God. While the delay means it will be exactly two years to the day that the order was placed which led to the case, we are patient people and will now await the next stage in the process and remain confident that our case is right and just.

"We have said in the past that the case has been a source of some stress but it has also offered us great strength in each other and in God."

Speaking ahead of the appeal this morning, McArthur insisted Ashers Bakery did not discriminate and they had taken issue with the "message on the cake and not the customer".

"We are looking forward to having the ruling of the Lord Chief Justice overturned," he said before going into the High Court in Belfast this morning.

"We believe the County Court got the original ruling wrong. Ashers does not discriminate against anyone. We took issue with the message on the cake not the customer. And as a family we believe we should retain the freedom to decline business that would force us to promote a cause with which we disagree."

He added: "As Christians we can't simply switch off our faith as we enter the workplace in the morning.

"To be a Christian at all is to strive to live for Christ in every corner of our lives. We served Mr Lee as we would any other customer, we were simply unwilling to endorse this campaign for a new law that so clearly goes against what the Bible said about marriage. And for that we have been punished.

"As Christians, we are law abiding citizens and we expect the law to protect us as much as anybody 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 process very difficult. We would rather not be here today. We knew we had to appeal not only for ourselves but on the behalf of other family businesses who could be forced to endorse or promote views with which they disagree,.

"Today we appeal to the Lord Chief Justice and colleagues to overturn the county court ruling, we appeal to them to recognise there is a big difference between refusing to serve someone because of their sexual orientation or political opinion and choosing not to endorse those ideas."