Ali Hili, who ran a gay nightclub in Baghdad but fled to Britain this year after receiving death threats, told The Times of London he knows of more than 40 men killed in recent months.
Hili claims Grand Ayatollah Ali al-Sistani, the most revered spiritual figure in Iraq, provoked the slayings by saying on his Web site in April last year that homosexuals should be killed in the "worst, most severe way."
"We could never envisage this happening when Saddam (Hussein) was overthrown," the 33-year-old Hili said. "I had no love for the former president, but his regime never persecuted the gay community."
Elsewhere in the city, a 34-year-old theater actor, who would only give his name as Bashar, said he has gone into hiding after a death threat. Two close members of his family have been killed by militants, who say they will carry on killing his relatives until he turns himself in.