The Archbishop of Canterbury has been urged to discipline a Scottish Episcopal cathedral over a reading of the Koran that denied Jesus was the son of God.

Justin Welby was asked to intervene by the conservative grouping GAFCON UK on Thursday after a service last week at St Mary's Cathedral, Glasgow, contained a recitation from the Islamic holy book.

The reader, Madinah Javed, went beyond the allocated passage translated in the service sheet to include verses which explicitly denied Jesus was God's son – a key Christian belief.

It is not clear whether this was authorised by the cathedral's Provost, Rev Kelvin Holdsworth, who has refused to speak to Christian Today.

Justin Welby, as head of the Church of England, has no strict authority over the Scottish Episcopal Church. But as the spiritual leader of the worldwide Anglican Communion, he can exert moral pressure over them at the next conference of global Anglican leaders.

A statement on the cathedral's website defends the reading but declined to comment specifically on the declaration Jesus was not the son of God.

"We listened with interest to the story that Muslims tell of the annunciation of Jesus in the Koran," Holdsworth wrote.

"Such readings have happened a number of times in the past in this and in other churches and have led to deepening friendships locally, to greater awareness of the thing we hold in common and to dialogue about the ways in which we differ."

Rev James Paice, a member of the GAFCON UK Taskforce, said he along with other Anglicans in the generally more conservative global south, "are appalled at the lack of discipline by the Scottish Episcopal Church at this continued syncretism and confusion over mission."

Paice's open letter follows outrage from conservative Anglicans and comes after a similar call for punishment by the conservative former Bishop of Rochester, Michael Nazir-Ali.

"The authorities of the Scottish Episcopal Church should immediately repudiate this ill-advised invitation," he said in a statement.

He also called for the Archbishop of Canterbury, Justin Welby, publicly to distance the Church of England and the wider Anglican Communion from the event.

"Christians should know what their fellow citizens believe and this can include reading the Koran for themselves, whether in the original or in translation. This is not, however, the same thing as having it read in Church in the context of public worship," he said.

Similiarly Rev Dr Gavin Ashenden, chaplain to the Queen, has called for Holdsworth to apologise and hinted he should quit his post.

"Some people will wonder if he has sufficient theological astuteness to remain in such a responsible office in times as fraught as these?" he wrote in a blog post. "Our interfaith relations require both integrity and competence. The strategy in Glasgow appears to have been short of both."

Christian Today has contacted the Cathedral and the Scottish Episcopal Church for a fuller response but they declined to comment further.

A spokesman for Lambeth Palace said they would pass on the complaints to St Mary's Cathedral but the Archbishop had no jurisdiction because the cathedral was outside the Church of England.