The former Archbishop of Canterbury has accused David Cameron of marginalising Christians.

In an article for a national newspaper, Lord Carey said it was “a bit rich” that the Prime Minister encouraged religious leaders to oppose secularism, when the Government appears to support it.

The Archbishop from 1991 to 2002 accused ministers of “aiding and abetting” discrimination against Christians.

The comments follow the Prime Minister's address to religious leaders at his pre-Easter Downing Street reception.

A spokesman for Downing Street rejected the claims.

Lord Carey, 77, said the government has increased Christian anxieties, particularly over its plans to legalise gay marriage.

He expressed alarm about a campaign by Labour MP Chris Bryant to turn the 700-year-old Parliamentary chapel of St Mary Undercroft into a multi-faith prayer room.

He claimed the plans, which would allow gay couples can get married there, were supported by the Government.

Writing in the Daily Mail, he said: “It was a bit rich to hear that the Prime Minister has told religious leaders that they should ‘stand up and oppose aggressive secularisation’ when it seems that his government is aiding and abetting this aggression every step of the way.

“At his pre-Easter Downing Street reception for faith leaders, he said that he supported Christians’ right to practise their faith. Yet many Christians doubt his sincerity.”

Lord Carey’s attack comes as a ComRes poll suggests more than half of Christians who backed the Conservatives at the last General Election, would not do so again.

It also revealed more than two-thirds feel they are part of a “persecuted minority.”

A Downing Street spokesman said: “This government strongly backs faith and Christianity in particular, including backing the rights of people wanting to wear crosses at work and hold prayers at council meetings.

“Christianity plays a vital part in the Big Society.”