Traditionalists have claimed that the Church of England may be split in two if an out gay cleric is appointed Bishop of Southwark.

Dr Jeffrey John, the Dean of St Albans, is the front-runner for the job and is thought to be supported by prime minister David Cameron.

Dr John is in a civil partnership and is celibate. In 2003, he was forced to turn down the post of Bishop of Reading in 2003 because opponents attacked his appointment as a gay man.

His selection to the shortlist was revealed yesterday and traditionalists have been quick to criticise the decision.

Canon Chris Sugden, the secretary of anti-gay group Anglican Mainstream, said there were a number of reasons why Dr John could not be appointed.

Speaking on Radio 4′s Today programme, he said: “He is in a registered civil partnership. Now the Church of England does not believe civil partnerships are the equivalent of marriage.

“Secondly, Dr John, by his own admission, was in an active gay relationship a number of years ago. And he is now said to be celibate, that is fine, one takes that at face value.

“However think of the parallel, say somebody was nominated to high government office, say the cabinet, and they had been involved in fiddling their expenses a number of years ago and never, never apologised or said it was wrong.

“It is breaking the law of the church in the sense of Christian teaching… the teaching still is that active homosexual practice is not compatible with the teaching of scripture.”

The Rev Paul Dawson of conservative evangelical group Reform told ITN: “Our view is that it would be a very serious step for the Church of England if he were to become a bishop and it would cause very serious damage within the Church of England itself.

“We think that if this were to happen, then the sort of split that has happened in America would be precipitated here.”

Southwark is known as a liberal diocese and Dr Giles Fraser, canon chancellor of St Paul’s cathedral, told the Today programme that Dr John “might well be the right person for the job”.

He added: “If you look at the job spec that the diocese of Southwark has put out, it says they want someone willing to honour the ministry of lesbian and gay clergy.”

The final decision on the appointment of bishops is made by the Queen on the advice of the prime minister.

Mr Cameron is understood to be minded to back Dr John’s appointment and has criticised the church in the past for its anti-gay approach to the appointment of senior clerics.