Pressure is mounting on the Church of England to adopt a formal liturgy for gay weddings after one diocese passed a landmark motion calling on bishops to act.

Hereford Diocesan Synod overwhelmingly voted on Thursday to call for official prayers and a dedication service for same-sex couples after their civil partnership or marriage.

The call mirrors the CofE's provision for divorced couples where – despite the Church holding to the teaching that marriage is a 'permanent and lifelong union of one man with one woman' – clergy can carry out blessings and formal dedication for couples getting remarried.

The Hereford vote stops short of full-blown gay weddings in church but bishops warned beforehand it will increase pressure for a wholesale change in the CofE's definition of marriage.

'Given that the Church of England in part defines its doctrine through its authorised liturgies, even if this service did not amount to a change in marriage, it would increase pressure towards such a change,' Hereford Bishop's Council warned delegates in a briefing paper before the vote.

The motion insists offering the service for gay couples would be optional, stating: 'It would contribute to a "mixed economy" in which different viewpoints could continue to exist.'

But the Bishop's Council warned before the vote that any result would cause 'pain' to either traditionalists or progressives.

'If the motion is approved, it will be experienced by others as a rejection of faithfulness to Scripture, and may lead those who hold the traditional position to feel unwanted in our diocese,' it said. 

Currently the Church's laws prevent clergy from marrying same-sex couples and 'services of blessing' should not be provided for those who enter into civil partnerships or same-sex marriages, a CofE spokesman said. 

Now it has been formally adopted by Hereford Diocese, the motion will go to a vote at the ruling general synod which next meets in February in London. While it may not be scheduled to be debated in the immediate future, it cannot be removed from the agenda 'until debated or resolved otherwise'.

The vote will send shockwaves around the Church of England and the wider worldwide Anglican Communion and will accelerate calls from some traditionalists for a separate Anglican structure in the UK.

Already a 'missionary bishop' from the conservative pressure group GAFCON has been planted to oversee conservative parishes in the UK and Europe who do not want to come under the authority of their official local bishop.

But the progressive lobby OneBodyOneFaith in the Church welcomed the move, describing it as 'a small step as we continue to journey together'.

A statement read: 'Of central importance is the principle of not compelling anyone to act against their conscience - but at the same time permitting those who wish to celebrate and affirm faithful and committed relationships, to act with integrity too.'

Susie Leafe, director of the conservative Anglican grouping Reform, said the vote ignored the Bible and Jesus' understanding of marriage being between one man and one woman as the 'understanding of the vast majority of the worldwide church for two millennia'.

She said: 'To ask for a service of Prayer and Dedication for a same-sex relationship represents a fundamental departure from this teaching.'

She added a same-sex blessing was fundamentally different to the Church's blessing for divorced couples. 'It is hard to see how the Church can offer such a service to those who believe Jesus was wrong in his understanding of marriage and therefore see no reason to seek forgiveness or change their ways,' she said. 

A CofE spokesman said the Church was aware of the vote and a debate at general synod would be held at a time chosen by its agenda setting Business Committee.

'The diocesan synod's decision does not change the teaching or practice of the Church of England, whether in Hereford or anywhere else in the Church,' the spokesman said. 

'It is recognised, however, that there is real and profound disagreement in the Church of England over questions relating to human sexuality and the House of Bishops has recently embarked on the preparation of a major new teaching document on marriage and sexuality.

'We are seeking to find ways forward rooted in scripture and the Christian faith as we have received it and which values everyone, without exception, not as a "problem" or an "issue", but as a person loved and made in the image of God.'