Lib Dems call for end to barriers to gay marriage
Lib Dem members have urged ministers to recognise gay marriage as a "distinctly liberal" step to a more equal society.
They supported a conference motion calling on "discriminatory" barriers to equal marriage rights to be removed.
One delegate told the conference that existing legal distinctions between marriage and civil partnerships "taunted" people who were not married.
Although Lib Dem ministers support the move, it is unlikely to have an immediate impact on government policy.
Lib Dem leader Nick Clegg has voiced his support for gay marriage in the past but David Cameron has urged caution over any immediate change to the law.
Civil partnerships, which came into force in 2005, give same sex couples the right to the same legal treatment across a range of matters as married couples.
But the Labour government stopped short of referring to such unions as marriages and campaigners say that those in civil partnerships are still discriminated against.
Lib Dem members supported a motion arguing that discrimination on the basis of sexual orientation was "unconscionable" and incompatible with the party's support for liberty and equality.
Delegates said civil partners did not enjoy the same rights as married couples and the UK was lagging behind other European countries, such as Spain and Sweden, which have recognised gay marriage.
"There should be equality," Brian Paddick, former Lib Dem London mayoral candidate said, recalling the "symbolism and importance" of his marriage to a man in Norway last year.
"If I want to marry my same sex partner, I should be allowed to."
As well as "opening" marriage and civil partnerships to all couples, party members backed calls for all religious organisations to conduct both religious and humanist ceremonies in places of worship if they wanted to do so - although stressing they should not be forced to.
Procedures should be put in place to enable a couple to "convert" a marriage into a civil partnership and vice versa without the need for a divorce or dissolving the partnership.
They also backed calls for people who wanted to change gender to remain within their existing marital or partnership arrangements without any legal implications and for same sex marriages conducted abroad to have equal legal status in the UK.
The motion was overwhelmingly passed although a handful of members said it was a step too far and risked losing the party voters.
Some Lib Dems see support for gay rights and further advances in the equalities agenda as a key way of defining themselves within the coalition.
During the election campaign, Mr Clegg strongly attacked Tory plans to give tax breaks to married couples - a policy which was sidelined after the election.
Former Lib Dem MP Evan Harris said the Tories had undergone a "remarkable transformation" in relation to their attitudes to gay and lesbian rights in recent years.
But he said "we need to test the new Tory commitment to equality" on the issue of gay marriage.
Arguing that the idea had "public acceptance", he added: "We need to seize the moment and push forward to full equality. There is still work to be done."
Lib Dem equalities minister Lynne Featherstone said the government would "listen very carefully" to the arguments made by campaigners.
The Conservatives have indicated they would consider the case for allowing civil partnerships to be reclassified as civil marriages - a move that some of their backbenchers would oppose.
David Cameron has said civil partnerships are working well and future changes must be approached with caution although he has indicated that where ceremonies can be held should be looked at.