After suggesting marriage rights for gay couples were a ‘rung on the ladder’ to legalising sex with animals, Lord Maginnis has said he is ‘disgusted’ that a Tory think tank supports the move and will campaign to challenge its private funding streams.

Lord Maginnis sat as a Ulster Unionist Party peer in the House of Lords until last month when the party leader withdrew the whip following anti-gay comments he made on a radio programme.

He had referred to homosexuality as “unnatural and deviant” in a debate on marriage equality. He said gay marriage rights were “not something private like your marriage or my marriage, this is something aggressive and demanding”, claiming gay relationships were not “equal” and would “devalue” marriage.

In an email to the think tank the Policy Exchange this week, copied to the Northern Irish Newsletter newspaper, Lord Maginnis insists he is “not homophobic” but said he would seek to jeopardise the organisation’s income because of it published a paper in support of equal marriage rights.

He wrote: “I spoke to someone last week – it may have been yourself – to express my disgust that a Tory think–tank would promote ‘same-sex’ marriage – which I now note they have re-titled ‘equal marriage’. At that time I was told that Dean Godson would contact me but he has failed to do so.

“Being a firm opponent of this perverse proposal – let the Government find its own way to cope with property and financial rights of people engaged in this way of life – I now find it necessary to campaign publicly against Policy Exchange, the wisdom of financing it by private sources and the dubious nature of its ‘independence’.

“I am not homophobic but totally oppose the ‘imposition’ of this practice on the institution of ‘marriage’ which derives its purpose and meaning from biblical sources. Please remove my name from your emailing directory.”

The Policy Exchange report ‘What’s In A Name? Is there a case for equal marriage?’ reasoned that gay and straight couples should be allowed an equal right to marry.

It reasoned that principles of religious freedom should allow faiths to marry gay couples if they wish, and that religious bodies “should not be forced by the State to hold a same sex marriage ceremony on their premises”.

It said: “Full equality would bring the final symbolic acceptance to a group only recently invited in from the cold.”

The Policy Exchange has said Lord Maginnis is “entitled to his own opinion”, while the newly-launched campaign group Equal Marriage Northern Ireland said it was “disgusted” by the peer’s latest comments.

A spokesman said: “Being discontent with merely displaying his obvious prejudice against the LGBT community last month with his now infamous “rung on the ladder to bestiality” comment, he appears to now be gearing up to actively campaign against the Policy Exchange group which in effect equates to campaigning against basic equality in our society.”

They added: “Love is a human experience not a political statement and marriage equality is a human right not a heterosexual or specifically Christian privilege.”

It criticised “circular dinosaur rhetoric” and advised Lord Maginnis it would be “much easier to convince the public that you are “not homophobic” if you refrain from public outbursts of intolerance such as your implicit suggestion that homosexuality; what you negatively refer to as “this practice” (as if it were unnatural or ought to be prohibited) is somehow abhorrent.”

The group added: “We thank the Policy Exchange for supporting equal marriage and hope to extrapolate more support within a Northern Ireland context.”

It said the “domino effect” was already beginning as Belfast City Council had announced its support for equal marriage earlier this month.