Bishops in the US dealt a death blow to hopes for unity in the worldwide Anglican Church when they approved in principle services for same-sex partnerships. The decision will finally split the Communion between Bible-based conservative evangelicals and liberal modernisers.

The bishops at the Episcopal General Convention voted by 104 to 30 to “collect and develop theological resources and liturgies” for blessing same-sex relationships, to be considered at the next convention in 2012.

The resolution notes the growing number of states that allow gay marriage, civil unions and domestic partnerships, and gives bishops in those regions discretion to provide a “generous pastoral response” to couples in local parishes. It was passed on Wednesday, hours after the Episcopal Church voted on Tuesday to allow the consecration of gay bishops. The motion passed by 99 to 45 among the bishops and by 72 per cent to 28 per cent among church deputies, made up of clergy and laity.

The decisions on gay consecrations and same-sex blessings end the uneasy truce agreed after the consecration of the openly gay Gene Robinson as Bishop of New Hampshire in 2003.

The General Convention in 2006 agreed a resolution that pledged the Episcopal Church to abide by two moratoriums on same-sex blessings and gay consecrations as requested by Dr Williams and the other 38 Primates. The resolutions now passed bring that truce to an end, and will be seen in the conservative-dominated evangelical churches of the “Global South” as an open declaration of war.

It ends years of tense and costly ecclesiastical polity, and finally nails the hopes of the Archbishop of Canterbury, Dr Rowan Williams, who has sacrificed his own liberal principles on the altar of church unity, to no avail. Dozens of meetings of bishops, archbishops, canon lawyers, clergy and lay theologians in Britain, Ireland, Jamaica and elsewhere, pages of dense reports and hours of prayer have been rendered redundant by the General Convention of the Episcopal Church of the US in Anaheim, California.

Church leaders led by Dr Williams must now manage the disintegration of a 70-million strong Communion of 38 provinces that can no longer maintain the facade of unity.

Bishop Dean Wolfe of Kansas, who warned that “sometimes it takes very little” to “move us from agreement to division”, asked the bishops at the convention to practise a “generous orthodoxy” to conservatives who opposed same-sex blessings.

But many conservatives are not at the convention, which ends today, because they have left to form a new parallel “province”, the Anglican Church in North America, which is seeking recognition from Dr Williams. A private member’s motion to be debated at the General Synod next February could confer this recognition, which will give Dr Williams his one hope of retaining a semblance of unity by letting two provinces, one liberal and one conservative, exist side by side in the US.

In a closed session at Anaheim, an ad hoc committee of bishops had been asked to study the resolution to find ways to keep the Episcopal Church within the bounds of the Anglican Communion while also allowing for same-sex blessings. However, Bishop Mark Lawrence, a conservative from South Carolina, said that an accommodation would not work. “I’m not interested in tweaking this,” he said. “It’s not the train that’s the problem — it’s the direction it’s going.”

At the start of the convention last week, Dr Williams said in a sermon to delegates: “I hope and pray that there won’t be decisions in the coming days that could push us farther apart.” At the General Synod in York at the weekend, he told friends he was confident that Episcopal Church leaders would take his concerns seriously.

Lambeth Palace declined to comment as the decisions taken by the Episcopal Church’s leaders showed that they saw no reason to place the concerns of the “mother Church” in England above the demands of their own worshippers.