An Ulster Unionist peer's claim that gay marriage is deviant has been branded reprehensible.
A gay and bisexual charity said the comments by Lord Ken Maginnis were ridiculous.
The Ulster Unionist Party has distanced itself from the views, aired on BBC Radio Ulster's Nolan Show today.
John O'Doherty, director of the Rainbow Project, said: "At a time when an Equality Commission survey has found that negative attitudes towards lesbian, gay, bisexual and transgender people in Northern Ireland have significantly hardened it is reprehensible that a senior politician should claim that people in loving and committed relationships are unnatural and deviant.
"Many LGB&T people feel isolated and vulnerable in their communities and the ridiculous claims made by Lord Maginnis only compound this isolation."
The senior politician claimed gay relationships were "a rung on the ladder" towards bestiality.
Referring to campaigns to allow the same rights for same-sex couples when it comes to marriage, Lord Maginnis said it all came down to sexual practice.
"Does that mean that every deviant practice has to be accommodated? Will the next thing be that we legislate for some sort of bestiality?" he asked.
Lord Maginnis moved to defend his argument when challenged.
"You've asked me to define it as I see it, as it affects my church, as it may affect children ... I just do not believe that we should be doing anything to encourage this deviant practice," he said.
"If my next-door neighbour is homosexual, I will treat him with the same day-to-day respect as I will treat the neighbour on the other side."
A survey by the Equality Commission has been looking into how attitudes towards people from different backgrounds have changed in Northern Ireland over the last six years.
The findings, published today, show increased negativity - including towards the gay community.
Just over a quarter of people surveyed said they would object to having a gay neighbour.
Democratic Unionist Party leader Peter Robinson`s wife Iris, a born-again Christian and former MP for Strangford, caused controversy in 2008 for calling homosexuality "an abomination", adding that with help gay people could be "turned around".
Her comments were made in the same week that a gay man had been badly beaten in a homophobic attack.
An online petition calling for then prime minister Gordon Brown to reprimand Mrs Robinson gathered 16,000 signatures.
While the UUP distanced itself from the remarks by Lord Maginnis, a call has been made for party leader Mike Nesbitt to take disciplinary action.
Alliance Party chief whip Stewart Dickson said he was appalled by the "outrageous" remarks.
"There is no way that Mike Nesbitt can get away with saying that Lord Maginnis was speaking in a personal capacity," he said.
"He was representing the UUP when he spoke and I am sure that many people will take his words as UUP policy until strong disciplinary action is taken."