David Cameron has been told to ignore his more right-wing backbenchers and introduce legislation legalising gay marriage as soon as possible.
Speaking in the House of Commons on Thursday, Labour's Angela Eagle said it was important to bring in the planned change soon to avoid leaving couples "in limbo".
Marking international day against homophobia and transphobia, Eagle said it was important to remember that there were still five countries where being gay is punishable by death and 76 where it remained illegal.
"We should pay tribute to all those who are bravely campaigning for equality around the world," she said.
In 2008 Eagle became the first female MP to hold a civil partnership ceremony.
The shadow leader of the Commons said equalities minister Lynne Featherstone to come to the House to explain when proposals for equal marriage would be introduced.
"This weekend the defence secretary it wasn't priority and the education minister said he was totally opposed," she said.
"But across the country there are couples who want to know whether to have a civil partnership or wait until the law is changed.
"What they don't want is to be in limbo while Conservative MPs fight amongst themselves and the government prevaricates.
"David Cameron said it was an important priority and I agree," she said. "The government should commit quickly to bringing forward legislation on equal marriage."
The prime minister has run into opposition from some right-wing Tory backbenchers over coalition plans to bring in equal marriage, with some even blaming the proposals for the party's dismal showing at the recent local elections.
Sir George Young, the leader of the Commons, told Eagle the government was "strongly committed to advancing equality" and was currently consulting on how to bring in gay marriage.
"She will know that we've lifted the ban on civil partenrships taking palce on religious premises," he said.
Speaking on the onternational day against homophobia and transphobia, Foreign Office Minister Jeremy Browne said: "It is sadly the case that in many countries Lesbian, Gay, Bisexual and Transgender people continue to suffer brutal violence and discrimination.
"These people are not making a political statement, or asking for special treatment, they just want to be free to be who they are and to love who they choose.
“These simple demands are not Western impositions but universal human rights we should all be able to take for granted. "
He added: "We strongly oppose any criminalisation of same-sex relations."