The Archbishop of Canterbury has criticised conservatives for planting a 'missionary' bishop after Scotland's Anglicans approved gay marriage in church.

It comes conservatives appointed Canon Andy Lines as missionary bishop, making him an alternative figurehead outside the official church structure and effectively prompting a split in the UK Anglican church.

Justin Welby's rebuke came in a blunt letter to leaders across the worldwide Anglican Communion accusing Lines and his colleagues of a 'cross-border intervention' and saying he would 'carry no weight' in the Church of England.

In an unusually direct intervention, Welby quoted one of Christianity's most formative edicts, from the Council of Nicea in 325 AD, condemning 'cross-border interventions' for the 'great disturbances and discords' they cause.

The letter to Anglican leaders, seen by the Mail on Sunday, will enrage conservatives who wanted Welby to reprimand the Scots for contravening the church's long-held teaching.

Instead the scolding was directed at them with Welby, as overall head of the Anglican Communion, saying there was no need for a missionary bishop in the CofE because worshippers could hold a range of opinions.

The fallout comes after the Scottish Episcopal Church changed their teaching on marriage, becoming the first British Anglican body to permit same-sex weddings.

The change, passed by a two-thirds majority across its ruling general synod, means the church no longer teaches marriage is 'between one man and one woman'.

Now it technically doesn't hold any position on marriage and its canon instead reads: 'In the light of the fact that there are differing understandings of the nature of marriage in this Church, no cleric of this Church shall be obliged to conduct any marriage against their conscience.'

The shift is designed to permit gay marriage without forcing clergy to oversee weddings between same-sex couples if they don't want to.

The method could be adopted across other Anglican churches as an attempt to avoid a rupture.

The Bishop of Cork, Paul Colton, suggested it could provide a way forward for the Church in Ireland as well, telling his local diocesan synod it 'represents a way forward for us too that recognises all integrities. It is worth considering in our debate here in Ireland.'

He quoted the Scottish Primus David Chillingworth who said 'the new canon itself affirms that there are differing views of marriage in our church.

'Nobody will be compelled to do anything against their conscience. We affirm that we are a church of diversity and difference, bound together by our oneness in Christ.'

Bishop Colton added: 'The reality is that there is such diversity and difference throughout the Church of Ireland too. Those differences and that diversity cannot be ignored.'