A split over same-sex marriage in the Scottish Episcopal Church (SEC) became a real possibility on Friday as clergy were given the option to switch allegiances to conservative bishops around the world.

Gafcon, the powerful traditionalist group including bishops and archbishops, offered to provide "alternative episcopal oversight" to Anglicans in the SEC who were unhappy with today's vote towards allowing same-sex marriages in the Church.

On Friday a strong majority of the SEC's general synod passed the first stage in the process to change the Church's teaching on marriage and remove the understanding it was between "one man and one woman".

In a letter released after the vote, the Gafcon UK Panel of Bishops said they offered "to provide alternative episcopal oversight, and thereby your recognition as faithful Anglicans by the worldwide Gafcon movement, which represents the majority of Anglicans worldwide".

The letter was signed by four bishops on behalf of Gafcon UK's panel and four other Anglican clergymen.

Written before the vote, it was released by the traditionalist Scottish Anglican Network in the immediate aftermath of the decision. It said the SEC was "dividing the church" over the issue of gay marriage and promised to "stand united with faithful Anglicans in Scotland seeking to uphold the plain doctrinal and moral teaching of the Holy Scriptures".

Bishop John Ellison, one of primary signatories to the letter, told Christian Today he was in contact with "orthodox Christian leaders in Scotland" in light of the synod's vote and any split would be up to them.

"We want to stand alongside them," he said. "What form that will take we can't say at this stage. Being Anglicans we are concerned that people are under proper oversight." He said Gafcon UK would facilitate alternative oversight, should Scottish Anglicans wish to switch.

"The wider Anglican Communion is deeply concerned about what is happening in Scotland and we will act on their behalf," he said.

"There is a two way perspective. We will wait to hear from Scottish Anglicans and then make contact with other leaders in the wider union."

The prospect of a split in loyalties among Anglican clergy in Scotland comes after the leader of Gafcon warned the Church of England had crossed a "line" recently with the appointment of a pro-same-sex marriage bishop in Liverpool.

In his first pastoral letter since he became head of Gafcon, the Most Rev Nicholas Okoh, the Archbishop of Nigeria, said the "focus of concern" for conservative Anglicans had been the "heresy" of North American episcopal churches but said:

"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."