Equalities Minister Maria Miller says the Government will publish the results of its consultation on redefining marriage before Christmas.
The Government says it has received a staggering 228,000 responses – the largest number in British Government history.
But that number appears not to include the names and addresses of a further half-a-million people, submitted by the Coalition for Marriage.
C4M officially submitted the names to the Home Office as part of the consultation process, but it appears they may be ignored.
The Prime Minister is committed to introducing same-sex marriage by 2015, but the plans have proved highly divisive.
Mrs Miller claims that any legislation will include additional “locks” so that churches which refuse to marry same-sex couples will be safe from the European Court of Human Rights.
But critics warn that the Government does not have the power to offer such assurances.
More than 610,000 people have put their names to a petition demanding that the divisive proposals be ditched by Mr Cameron.
The petition, run by the Coalition for Marriage, has been signed by politicians, academics and swathes of the public.
Last week the Coalition for Marriage said Mr Cameron made a “catalogue of mistakes” in a letter claiming the public supports redefining marriage.
The group warned the letter to a former Government minister is “misleading” and “riddled with errors”.
Mr Cameron falsely claimed all the polls showed support for redefining marriage. In fact, the polls showed the Conservatives could lose up to 1.1 million votes over the issue.
And Conservative MP Edward Leigh has said it is “very foolish to muck about” with marriage.
Edward Leigh, the MP for Gainsborough, wrote a letter to a local paper highlighting the unprecedented amount of correspondence he has had on the issue.
He said: “No subject has ever been the cause of greater concern to those in Gainsborough who write to me than that of the Coalition’s plan to introduce legislation to redefine civil marriage to include same-sex couples.”