The leader of worldwide evangelical Anglican Christians has accused the Church of England of "normalising" the "false teaching" of the US Episcopal Church over gay marriage.

Archbishop of Nigeria Nicholas Okoh, chairman of the Global South orthodox Anglican group Gafcon, says a "line has been crossed" with the appointment of an American bishop who supports blessing same-sex unions to a post in the Liverpool diocese.

The Akure diocese in Nigeria, which was twinned with the  Liverpool diocese, has also formally severed its links following the appointment of Susan Goff, a suffragan in the Virginia diocese in the US Episcopal Church, as an honorary bishop in Liverpool.

In his pastoral letter, Archbishop Okoh says: "In the beginning, the focus of our concern was North America and we thank God that he has raised up the Anglican Church North America as a new wineskin in that continent.

"Now our concern is increasingly with the British Isles. A line has been crossed in the Church of England itself with the appointment of Bishop Susan Goff, of the Episcopal Diocese of Virginia, as an Assisting Bishop of Liverpool.

"The false teaching of the American Episcopal Church has been normalised in England and this divisive act has meant that the Church of Nigeria's Akure Diocese has had no alternative but to end its partnership link with Liverpool Diocese."

Archbishop Okoh writes that he is convinced Gafcon is a movement called into being and sustained by the Lord of the Church himself. "In every age, the devil is at work to destroy the Church, but we stand firm in the confidence that the gates of hell shall not prevail against it," he says.

"We therefore preach the gospel, make disciples and commit ourselves to prevailing prayer, knowing that the most dangerous attack on the Church today is not persecution from the outside, terrible though that can be, but a globalised secular ideology which has established itself inside the Church."

The divisions which have been so destructive in recent years have come about because "some have chosen to abandon biblical doctrine."

He warns that it has become "increasingly clear" since the meeting of the Anglican Consultative Council in Lusaka last month that those traditionally entrusted with leadership in the Communion will do nothing to call them to repentance.

Gafcon, which began in 2008 with a conference in Jerusalem, is planning its next meeting for 2018.

The UK's own conservative evangelical group Reform has also objected to Goff's appointment.

In a separate letter to the Liverpool diocese, Bishop of Akure Simeon Borokini writes that the three-way partnership between the dioceses of Liverpool, Akure, and Virginia must now end. 

"Susan Goff is in favour of blessing same sex unions and this has been a part of the litigation against the orthodox in Virginia," he says. "Therefore, in view of the above and being aware of the fact that Nigeria does not support same sex marriage, we in Akure Diocese cannot have any link with Liverpool diocese."

In a statement on the Liverpool diocesan website, Bishop of Liverpool Paul Bayes says he asked Goff over a year ago to become an honorary assistant bishop. As an overseas bishop, she will be able to minister but not take part in ordinations. Bayes says: "I remain delighted that our ministry here will be enriched by what Bishop Susan will bring to us as a teacher, pastor and disciple. She will also be able to hear and to engage with the wide range of views in our diocese on the way the Gospel is understood in these days.

"It seems that this invitation has caused the Diocese of Akure, Nigeria, which has been another of our link dioceses, to issue a statement indicating that they no longer wish to be in a link-relationship with Liverpool. I regret this. I would prefer to walk together with Akure as well as with Virginia, within the one Communion whose life we share.

"I have not yet received formal notification directly from the Bishop of Akure, but as and when I do I shall write to him expressing this regret. If our partners choose to close this door, this is a matter of sorrow for us but of course we respect their decision as free partners in a free relationship." He indicates that if this is the case, he might pursue the possibility of a link with another diocese, in Ghana.