The party whip has been withdrawn from Ulster Unionist peer Lord Ken Maginnis after he linked homosexuality to bestiality.
The long-serving party veteran, of Dungannon, Co Tyrone, condemned "unnatural" and "deviant" practices in a radio interview on Wednesday.
Party leader Mike Nesbitt has said the party's position on gay marriage was that it was a matter of personal conscience, and that was reaffirmed by party officers over the weekend.
The leader held a meeting with Lord Maginnis, after which a UUP spokesman said: "Concluding the meeting, Mr Nesbitt informed Lord Maginnis that he was withdrawing the party whip.
"While this situation pertains, any public comment made by Lord Maginnis, in the media or elsewhere, should not be considered to represent the views of the Ulster Unionist Party. Mr Nesbitt remains respectful of Lord Maginnis's enormous contribution to the Ulster Unionist Party, to Northern Ireland and to the making of peace, and is hopeful a resolution can be found to enable Lord Maginnis to again contribute to the party's development."
During a discussion on gay marriage on BBC Radio Ulster's Nolan Show, Lord Maginnis said: "This is based on sexual practice, now does that mean that every deviant practice has to be accommodated? Will the next thing be that we legislate for some sort of bestiality?"
Afterwards, the party distanced itself from the comments, while a gay and bisexual charity said his remarks were "reprehensible".
Lord Maginnis of Drumglass was elevated to the House of Lords in 2001. He was a member of Parliament for Fermanagh and South Tyrone between 1983 and 2001, and was also a councillor on Dungannon District Council. During his time as an MP, Lord Maginnis was party spokesman for internal security and defence.
Some unionist politicians and leading figures in evangelical Protestant churches in Northern Ireland have been accused of homophobia over the last four decades. Retired Northern Ireland First Minister Ian Paisley in 1977 launched a campaign called "Save Ulster from sodomy" as he and his followers tried to prevent the liberalisation of gay sex laws.
Lord Maginnis said he was disappointed by Mr Nesbitt's decision, saying: "You can't withdraw a party whip from somebody who is a cross-bench peer. I quite simply see this as a shallow, meaningless gesture."