By Michael Holden
LONDON (Reuters) - Britain's anti-European Union party has scooped up support from voters traditionally loyal to Prime Minister David Cameron's Conservatives after the government announced plans to allow gay couples to marry, three polls showed on Sunday.
A large number of Conservative lawmakers as well as the Church of England oppose the plans for same-sex marriage announced on Tuesday, although the move is generally popular across the country.
UKIP, which wants Britain to exit the EU, has pledged to exploit Conservative divisions over the issue and polls showed its support reaching new highs, putting it in third place ahead of Cameron's junior coalition partners the Liberal Democrats.
Both a ComRes survey for the Independent on Sunday and Sunday Mirror newspapers and the Observer paper's Opinium poll had the Conservatives on 29 percent, 10 points behind the opposition Labour Party, with UKIP on 14 percent.
A third poll by Survation for the Mail on Sunday newspaper had the Conservatives on 30 percent, Labour on 38 percent and UKIP again with 14 percent. All three surveys had the Liberal Democrats trailing in fourth on 9 percent or less.
"The Conservatives are leaking votes to UKIP - one in five of the party's 2010 voters say that they now intend to vote UKIP," said Andrew Hawkins, chairman of ComRes.
"There is good evidence that many UKIP voters are erstwhile Conservatives on the rebound: large proportions are negative about David Cameron and (finance minister) George Osborne on the economy, and about Mr. Cameron's handling of gay marriage."
UKIP polled more votes than the centre-right Conservatives in two recent elections for parliamentary seats, partly helped by Britons' discontent at government austerity measures along with a growing anti-EU sentiment shared by many within Cameron's party.
Despite success in elections for the European Parliament, UKIP has never won a seat at Westminster and commentators say its rise in support is likely to hurt the Conservatives at the next election in 2015 rather than lead to an electoral breakthrough.
"Unless we see some really substantial change from the government and the Labour party ... with a U-turn on Europe, open-door immigration, gay marriage and other things, then there's no reason to think that this level of support for UKIP can't be maintained," its leader Nigel Farage told Sky News.
He hopes UKIP's opposition to gay marriage will contribute to this, and argues that current laws which allow gay couples to form civil partnerships conferring the same legal rights as marriage are sufficient.
While polls indicate a majority of Britons do support the change, they have also shown far fewer of those who voted Conservative at the last election in 2010 are in favor.
Political analysts have suggested the gay marriage plans are a way for Cameron to broaden his party's support and burnish its liberal values. However the Survation survey found two-thirds of those it polled thought he was supporting gay marriage to win "trendy votes" rather than because he thought it was right.
(Editing by Rosalind Russell)