A row over homophobia in politics escalated last night as the Conservative leader, David Cameron, was accused of pushing "Victorian values" on to the 21st-century concept of the family.
Harriet Harman, Labour's deputy leader, accused the Tories of "hypocritical moralising" for putting forward plans to support traditional family values and make divorce more difficult.
A bitter debate about which political party has the right to claim the "pink vote" overshadowed Gay Pride yesterday, when up to a million people marched through the capital.
Ed Balls, the Schools Secretary, stoked the row by criticising the "fierce opposition" to gay rights legislation by the Conservatives in Parliament, even though Mr Cameron has backed some of the measures. He became the fifth minister to claim that Labour was winning the battle for Britain's three million gay votes by declaring that the Government had led the way on overturning homophobic legislation such as Section 28.
His remarks came as it emerged that the Conservatives are considering a raft of "family values" policies which critics said had echoes of the ill-fated "Back to Basics" campaign of the John Major government.
A review by the former leader Iain Duncan Smith on behalf of Mr Cameron, hailed as a "Tory blueprint for the family", proposed tax breaks for married couples and laws to make divorce more difficult.
Ms Harman, who is also Equalities Minister, told The Independent on Sunday: "Families won't want to be lectured by anybody, whether in the Cabinet or the shadow Cabinet, about how to lead their lives, especially as politicians haven't proved themselves more likely to stay married than the rest of the population.
"Practical help is what is needed for families, not hypocritical moralising."
On the issue of allegations of homophobia in politics, Ms Harman said: "I would be more than happy for the question of gay rights to be not a political issue at all. No one wants to see prejudice in schools and children being homophobically bullied. But there is still a drag anchor in the Tory party which has not changed."
Mr Duncan Smith's plans did not appear to cover same-sex civil partnerships. However, Mr Cameron has indicated that an existing Tory commitment for tax breaks for married couples will cover gay marriages.
The Liberal Democrat leader Nick Clegg said last night: " On a weekend where they are trying to be the great friends of the gay community, the Tories are also trying to be the great advocates of the traditional Victorian family values. This is not so much Back to Basics, more them trying to have their cake and eating it."
Denis MacShane, the Labour former minister, said: "David Cameron has a real problem with modern relationships as he panders to those who want to imprison women in loveless marriages by making divorce more difficult while claiming he is pro-gay.
"Cameron is getting into bed with gay-bashing European parties in the European Parliament while saying he is pro-gay in Notting Hill. He wants to appease his traditional right and hope no one notices his forked tongue. It is undignified politics."
The row began last week when Mr Cameron apologised for his party's introduction of Section 28, the law that banned the promotion of homosexuality in schools, sparking criticism from two gay ministers.
Ben Bradshaw, the Culture Secretary, triggered controversy by saying that a "deep strain of homophobia still exists on the Conservative benches", while the Foreign Office minister Chris Bryant said: "If gays vote Tory, they will rue the day very soon."
The Tory leader voted in 2003 for the retention of Section 28, but has voted in favour of other gay rights legislation. Angela Eagle, the Pensions minister, said he was one of only 29 Tories to vote in favour of equality in goods and services.
Alan Duncan, one of two openly gay members of the shadow Cabinet, said yesterday that the comments by Mr Bradshaw and Mr Bryant were "scurrilous".