British MPs pass gay marriage bill

The British gay marriage bill survived a stormy passage through parliament, with some members of Prime Minister David Cameron's party voting against it.

UK gay rights campaigners are celebrating, with same-sex marriage likely to become law within days.

British MPs have passed a bill legalising same-sex marriage in England and Wales, paving the way for the first gay weddings in 2014.

MPs decided not to oppose a number of minor amendments to the Marriage (Same Sex Couples) Bill proposed by the upper House of Lords.

The legislation is now expected to receive official assent from head of state Queen Elizabeth II later this week after MPs agreed to changes such as ensuring protections for transgender couples.

Jubilant gay rights activists had danced outside parliament on Monday night as the government-backed bill passed unopposed through the upper House of Lords, where some members wore pink carnations.

A spokesman for the culture ministry, which is overseeing the new law, said the bill would probably receive royal assent on Wednesday or Thursday.

"But we are looking at seeing the first gay weddings in the middle of 2014 because there are various issues to sort out, such as its impact on pensions," the spokesman said.

Government computer systems also need to be updated to allow same-sex marriages to be registered, at an estimated cost of STG2 million ($A3.34 million).

But the government hopes legalising gay marriage will bring an overall boost to the economy, estimating that the change could bring in up to STG14.4 million a year for caterers, hotels and the rest of the wedding industry.

The bill survived a stormy passage through parliament, with dozens of members of Prime Minister David Cameron's own Conservative party voting against it.

An attempt in the Lords last month to kill off the legislation with a "wrecking amendment" failed.

Deputy Prime Minister Nick Clegg, who leads Cameron's junior coalition partners, the Liberal Democrats, said the new law would ensure that gay couples felt "recognised and valued, not excluded".

Gay rights activists have vowed to press on for equal marriage in the United Kingdom's other two nations, Scotland and Northern Ireland.

France became the 14th country to legalise same-sex marriage in May, joining The Netherlands, Spain, Canada, South Africa, Norway, Sweden, Portugal, Iceland, Argentina, Denmark, Uruguay, Belgium, and New Zealand.

Gay couples can marry in 13 US states, as well as in the capital Washington DC, while parts of Mexico also allow same-sex marriage.