Church leaders from Africa and Asia are threatening to walk out of a crucial meeting chaired by the Archbishop of Canterbury unless American bishops drop their support for gay marriage.

Archbishop Justin Welby last year invited the leaders of the worldwide Anglican Church to the summit in Canterbury next week in a ‘make or break’ effort to avert a permanent split over homosexuality.

The row has torn the Church apart for a decade – with conservatives accusing liberals of abandoning the word of God by backing openly gay bishops and marriages for gay couples – and the Archbishop wants to broker a deal to allow both sides to co-exist peacefully.

Archbishop Justin Welby last year invited the leaders of the worldwide Anglican Church to the summit in Canterbury next week in a ‘make or break’ effort to avert a permanent split over homosexuality

But insiders said a hardcore of eight to 12 conservative archbishops from Africa and Asia are preparing to quit the meeting on the first morning unless the liberal Americans ‘repent’ or the Archbishop throws them out.

In what would be a massive challenge to Archbishop Welby’s authority, the conservatives, who represent some of the biggest of the 38 individual Churches in the worldwide ‘Communion’, are then likely move to their own headquarters nearby for the rest of the meeting.

While they are unlikely immediately to break their historic ties with the Archbishop of Canterbury – the nominal head of the Communion – they would boycott future official meetings and set up a parallel church, drawing away traditionalists from the Church of England.

The Mail on Sunday has learned that feelings are running so high that the three most powerful leaders, the Archbishops of Nigeria, Kenya and Uganda, were last week on the brink of snubbing the meeting altogether, but were persuaded to attend by colleagues still hoping to force concessions from Welby.

Sources said they have lost patience with the Archbishop’s refusal to discipline the liberals for ignoring official policy urging them to refrain from creating gay bishops or approving gay marriage without widespread agreement.

Insiders said a hardcore of eight to 12 conservative archbishops from Africa and Asia are preparing to quit the meeting on the first morning unless the liberal Americans ‘repent’ or the Archbishop throws them out

But liberal leaders have said Archbishop Welby has assured them that no one will be expelled from the meeting.

The Archbishop will instead propose that the Communion becomes a more loosely linked ‘federation’ to keep everyone in the ‘family’ – which aides have compared to ‘moving into separate bedrooms’ rather than full-scale divorce.

The bitter divisions led Archbishop Welby to postpone last year’s Lambeth Conference, the regular gathering of all Anglican bishops from around the world that has been held nearly every decade, except during the two world wars, since the 1860s.

The last, in 2008, was boycotted by key conservatives furious with the liberal American Church for consecrating an openly gay bishop, Gene Robinson, in 2003. The Americans accuse conservatives of fostering homophobic attitudes.