The Scottish cabinet is expected to discuss plans to legislate for same-sex marriage when it meets later.
SNP ministers, who favour the move, are due to announce legislation this week in the wake of a consultation which resulted in 80,000 responses.
The proposals, which would see Scotland become the first part of the UK to introduce the policy, have provoked opposition from some religious groups.
The Catholic Church and Church of Scotland strongly oppose the policy.
Same-sex couples in Scotland currently have the option to enter into civil partnerships and the Holyrood government has insisted no part of the religious community would be forced to hold same-sex weddings in churches.
The introduction of gay marriage has been backed by a “rainbow coalition” of organisations, including The Equality Network, Amnesty International, Unison and the Humanist Society of Scotland, as well as political parties.
Faith groups, including the United Reformed Church, the Quakers, Buddhists and the Pagan Federation also support the move, but some big religious groups are against the idea of redefining marriage as a union between a man and a woman.
Britain’s most senior Roman Catholic cleric, Cardinal Keith O’Brien, has branded the plans a “grotesque subversion of a universally accepted human right” and urged the Scottish government to hold a referendum on the proposals.
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Cardinal O’Brien, who leads the church in Scotland, previously authorised a plan to raise £100,000 through special church collections to support the Scotland For Marriage campaign against same-sex marriage.
The issue also caused a split within the SNP, after a parliamentary motion tabled by party MSP John Mason, stating no person or organisation should be forced to be involved in or to approve of same-sex marriage, led to accusations by some of his colleagues that his actions encouraged discrimination.
Gordon Wilson, a former SNP leader, has also warned plans for same-sex marriage could “alienate” people considering voting for independence in the 2014 referendum.
The Scottish cabinet has already held initial talks on the way forward, and has asked for further detail.
Although civil partnerships in Scotland offer the same legal treatment as marriage in areas such as inheritance, pensions provision, life assurance, child maintenance, next of kin and immigration rights, they are still seen as distinct from marriage.
A man and a woman can opt for a religious or civil marriage ceremony, whereas a same-sex partnership is an exclusively civil procedure.
The UK government, which is consulting on changing the status of civil ceremonies to allow gay and lesbian couples in England and Wales to get married, wants to make the change by 2015.
