ALEX SALMOND appeared set on a collision course with the Catholic Church and other religious groups last night as he ordered a special committee to finalise plans for legalising gay marriage and ruled out a referendum on the issue.

A firm decision on whether to permit same-sex unions had been expected at yesterday's cabinet meeting, but was postponed to allow further work by a group chaired by Deputy First Minister Nicola Sturgeon, who has led the SNP Government's plans on gay marriage.

The pause was initially greeted with dismay by gay rights campaigners who have seen several deadlines slip, and with scepticism from Labour and the LibDems, who accused the First Minister of weak leadership and kow-towing to those opposed to same-sex marriage.

However, subsequent Government briefings suggested ministers were moving towards approval of both registry and church weddings for same-sex couples, who are currently limited to secular civil partnerships.

It emerged Ms Sturgeon's cabinet sub-committee would examine how to protect "religious freedom and freedom of speech" if gay marriage was legalised and report directly to the First Minister, who will announce the way forward later this month without another cabinet meeting.

Her group, which includes Education Secretary Michael Russell and Justice Secretary Kenny MacAskill, and is being advised by Lord Advocate Frank Mulholland, will look at ensuring churches and religious celebrants who are opposed to gay marriage can opt out of ceremonies. Mr Russell's inclusion in the group also suggests it will examine how the subject of gay marriage will be approached in schools.

The Catholic Church and Muslim leaders have repeatedly raised fears they could be compelled to hold services against their will because of the 2010 Equality Act which makes discrimination on sexual grounds illegal. The SNP and UK Coalition governments are now in talks about amending the Act at Westminster to ensure no person or group is forced to hold services.

One SNP MSP who supports gay marriage told The Herald: "I'm confident it's moving in the right direction. I think the decision has been taken in principle and the sub-committee is now crossing Ts and dotting Is."

Government officials also revealed the cabinet had rejected a recent call from the Catholic Church for a referendum on same-sex marriage on the grounds it was an issue of conscience, not constitution. The Government said the cabinet wanted to get "both the principle and the detail of the decision right", and, in another hint, said if a bill to legalise gay marriage was brought before Parliament, there would be a free vote, allowing ministers to oppose it.

At least three junior ministers – Fergus Ewing, Roseanna Cunningham and Michael Matheson – are understood to oppose gay marriage on religious grounds, while Gaelic Minister Alasdair Allan may also find it difficult to support gay marriage, given strong opposition in his Western Isles constituency.

SNP ministers said last year they tended towards support for same-sex marriage on equality grounds, but a consultation on the issue attracted a record 77,000 responses, the majority of them hostile.

Cardinal Keith O'Brien, the leader of the Catholic Church in Scotland, has already announced plans for a £100,000 fighting fund to head off a change in the law.

The Government's determination to push ahead with its plans means it now faces a damaging battle with its critics in the run-up to the 2014 independence referendum. Former SNP leader Gordon Wilson last night urged the cabinet to "ditch this absurd proposal", adding: "For the SNP, independence must come before political correctness. Alienating a large section of the Scottish electorate on the eve of a historic referendum on independence makes little political sense."

Scotland for Marriage, the evangelical group opposed to same-sex marriage, said redefining marriage would "unravel hundreds of years of matrimonial law, creating legal and cultural chaos".

Tom French, policy co- ordinator at the Equality Network, which has been at the forefront of the campaign for same-sex marriage, said: "Same-sex marriage is supported by the majority of Scots and the majority of MSPs. It is now vital to the Government's credibility a clear and positive decision is announced before the end of the month."

Glasgow MSP Drew Smith, Labour's social justice spokesman, said: "This display of weak leadership on such an important issue will have people questioning who is calling the shots in the SNP cabinet. A decision on this issue is long overdue and any further delay from Alex Salmond is unacceptable."

Scottish LibDem leader Willie Rennie said SNP dilly-dallying on the issue put the Government's credibility on equality at risk.

Only a handful of faiths have expressed any interest in conducting gay marriages in Scotland – Liberal Judaism, Unitarians, Quakers, the Metropolitan Community Church and the Pagan Federation.