One Canadian diocese has already unilaterally approved a rite for such blessings, and officials believe there is little doubt that the Synod will validate its decision.

Although illicit gay blessings are widespread in the Anglican Church, such a vote would be seen as the first clear endorsement of the practice by an entire province.

It would represent a fresh blow to the authority of the Archbishop of Canterbury, Dr Rowan Williams.

The Canadian decision to debate gay blessings in May, rather than deferring it, also represents the first serious test for Dr Williams's Lambeth Commission, set up in October to head off schism.

Dr Williams and the commission have strongly urged the warring parties to avoid exacerbating tensions until the commission has had time to report at the end of the year.

One of the strongest critics of homosexuality, the Primate of the Southern Cone in South America, Archbishop Gregory Venables, said this was "another symptom" of the schism that already existed.

"It is clear that the irreconcilable contradictions in ... Anglicanism can no longer be disguised by the mask of inclusive language and jolly photo-calls," he added.

A spokesman for the Canadian Church said, however, that the motion was merely to recognise the status quo in Canada, rather than make a final ruling on the morality of homosexuality.

"Whatever we do to try to face our reality here is likely to cause some stress within the Communion," said Canon Eric Beresford. "But I hope we can attempt to do it in a way that minimises that."

Dr Williams and his fellow primates - the heads of the 38 individual provinces which make up the 70 million-strong Anglican Communion - declared in May last year that they could not support rites for same-sex blessings.

Within hours, however, the liberal Canadian Bishop of New Westminster, the Rt Rev Michael Ingham, published a rite, and Anglicanism's first officially sanctioned gay "marriage" took place in a Vancouver church.

The damage was compounded in November by the consecration of Canon Gene Robinson in New Hampshire as Anglicanism's first openly gay bishop, despite a warning from primates that this would "tear the fabric" of the Church.

In spite of Dr Williams's efforts at conciliation, the conservatives in Africa and Asia and liberals in America and Canada have become increasingly entrenched.

Several other Canadian dioceses have said they want to follow New Westminster and approve gay blessings if the province gives the go ahead.

END