The family of the loyalist Alan McCullough, missing since last week, should be told if the UDA has taken him and what has happened to him.
The Loyalist Commission, an umbrella group involving three loyalist paramilitary organisations, unionist politicians and Protestant churchmen, issued the appeal yesterday urging the UDA to make it clear if it was responsible for the disappearance.
The police have said the lack of information about Mr McCullough put an "inhuman" burden on his family. The UDA has denied involvement.
An Ulster Unionist councillor, Mr Chris McGimpsey, said last night: "This should be resolved through the Loyalist Commission. If such a resolution is not forthcoming then I would respectfully call upon those Christian ministers who currently sit within the commission to withdraw."
Mr McCullough (21), an associate of jailed UDA 'C' Company leader Johnny Adair, was last seen near his home last Wednesday. There has been no sighting since.
He had left Northern Ireland last February following the intensification of the feud within the UDA after the murder by Adair's men of its South Antrim commander, Mr John Gregg.
Mr McCullough left for Scotland along with others associated with Adair and his family.
It is understood he returned recently.
Adair remains in Maghaberry prison in Co Antrim after the Northern Secretary, Mr Paul Murphy, revoked his early release licence last January.
Speaking last night, the missing man's mother, Barbara, said her son had been "200 per cent" sure it was safe to return.
However, she told the BBC she feared her son may be dead. "Over the years I've learned to trust nobody," she said. Asked if she was hopeful of seeing her son again, she said: "At this stage I just don't know."
Mr McCullough's brother Kenny has also made a public appeal for information.
On Tuesday, PSNI officers removed a small boat from the harbour in Carrickfergus, Co Antrim for forensic examination.
Detectives investigating the disappearance of another man, Mr Gareth O'Connor (24) in Co Armagh also fear they are searching for a body.