Authorities in Northern Ireland have U-turned on a threat to de-register churches if they did not state their position on conducting same-sex weddings.

Churches in the province were given just a few weeks to respond to a letter from the General Register Office (GRO) informing them that they needed to fill in a form confirming whether they would conduct gay weddings.

In the letter, churches were warned that if they failed to respond before 17 August – the middle of holiday season - they would not be permitted to carry out any weddings at all.

The Christian Institute said the threat, if carried out, would have amounted to a "blanket ban" on church wedding ceremonies.

Its lawyer, Sam Webster, wrote to the GRO last week to challenge the request, stating that the law in Northern Ireland permits churches to opt in to performing same-sex weddings but does not require them to opt out.

The GRO has since backtracked on its demand, calling the letter "an error".

In a statement published in The Newsletter, it said: "We apologise for this. We will be issuing an updated letter to all religious bodies to clarify that all religious officiants on the Registrar General's current register are regarded as opted out of performing same sex marriages.

"No officiants will be removed from the register and any religious bodies wishing to perform same sex marriages must opt in by completing the form issued with the letter."

The Christian Institute received its own letter from the GRO stating that a new letter was being sent out to churches "to highlight the mistake and apologise unreservedly for this error".

Simon Calvert, Deputy Director for Public Affairs at The Christian Institute, said: "We are grateful to the GRO for responding to the concerns about this ultimatum and for promising to put the matter right. I am sure churches will welcome the apology.

"This is important as the GRO sets about reassuring places of worship that they can continue to carry out weddings – the union of one man and one woman – and do not need to re-register in order to 'opt out' of conducting same-sex weddings."

"Quite how this letter came to be issued in the first place is a question which has yet to be answered. It was a crass way to handle an issue that is highly controversial amongst the churches, the vast majority of which believe as a matter of deep doctrinal conviction that marriage is the union of one man and one woman.

"The number likely to opt in is very small. In England, for example, 22,500 non-Anglican places of worship are registered for weddings and only 250 of those are registered for same-sex weddings."