Their decision stems from the decision this month of the Church of England's governing body, the General Synod, to allow clergy to bless couples in same-sex marriages.

The conservative Global South Fellowship of Anglican Churches (GSFA), which claims to speak for 75% of Anglicans worldwide, said in a statement on Monday that the C of E had "departed from the historic faith" and disqualified itself as the "mother church" of the Anglican communion.

The statement, signed by 10 primates, said: "The GFSA is no longer able to recognise the present archbishop of Canterbury, the Rt Hon & Most Revd Justin Welby, as the 'first among equals' leader of the global communion."

Welby had led his bishops in recommending that clergy be allowed to bless couples in same-sex marriages, knowing that it was "contrary to the faith and order of the orthodox provinces of the communion whose people constitute the majority in the global flock".

The C of E and other churches, including those in Scotland, Wales, the US and New Zealand, that allow same-sex marriage or blessings had "taken the path of false teaching", said the statement. "This breaks our hearts."

The recommendation put forward by C of E bishops to endorse optional blessings, but continue to prohibit same-sex marriages in church, was intended to be a compromise that would end decades of painful divisions on sexuality.

But progressives were furious that, in their view, the C of E would continue to treat same-sex couples as "second class", and conservatives were angry that the church appeared to be turning its back on traditional teaching on marriage and sexuality.

Welby welcomed the new position but said he would not personally offer same-sex blessings for the sake of unity in the global Anglican church. He also reportedly told MPs that he would rather see the C of E disestablished than for the global church to split over sexuality.

Immediately after the synod meeting in London, Welby flew to Accra, the capital of Ghana, to meet global church leaders. He told them: "I was summoned twice to parliament and threatened with parliamentary action to force same-sex marriage on us."

After the synod vote, Henry Ndukuba, the archbishop of the Church of Nigeria, which represents about a third of Anglicans worldwide, said the change of stance was "deviant" and it explained the C of E's "terrible decline, loss and irrelevance in the secular and post-Christian western world".

Jackson Ole Sapit, the archbishop of Kenya, criticised the "powerful secular voices that have captured the C of E" and said he was "saddened by the departure of our mother church from the true gospel".

Stephen Kaziimba, the archbishop of Uganda, said: "The C of E has departed from the Anglican faith and are now false teachers."

Since becoming archbishop of Canterbury 10 years ago, Welby has sought to hold the global church together in the face of bitter disagreements over sexuality. His approach has been to try to persuade bishops, clergy and parishioners to "walk together" despite apparently irreconcilable differences.

Last summer, the Lambeth conference, a once-a-decade meeting of Anglican bishops from all over the world, was boycotted by the primates of Nigeria, Rwanda and Uganda, who jointly represent about 30 million Anglicans, over the issue of sexuality.

The statement on Monday from the GSFA said their withdrawal of support for Welby as leader of the global church should be received by him as "an admonishment in love".

A Lambeth Palace spokesperson said: "Deep disagreements that exist across the Anglican communion on sexuality and marriage are not new."

In relation to the statement, they said "we fully appreciate their position", but "no changes to the formal structures of the Anglican communion can be made unless they are agreed upon" by all the body's leaders and councils.

However, the spokesperson added, Welby had told last week's meeting in Ghana that "these structures are always able to change with the times".

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