Being gay in Baghdad is dangerous and secrecy is paramount
Gay Iraqi men are being murdered in what appears to be a co-ordinated campaign involving militia forces, the group Human Rights Watch says.
It says hundreds of gay men have been targeted and killed in Iraq since 2004.
So-called honour killings also account for deaths where families punish their own kin in order to avoid public shame.
The report says members of the Mehdi Army militia group are spearheading the campaign, but police are also accused - even though homosexuality is legal.
Witnesses say vigilante groups break into homes and pick people up in the street, interrogating them to extract the names of other potential victims, before murdering them.
"Murder and torture are no way to enforce morality," said HRW researcher Rasha Moumneh, quoted in the report.
"These killings point to the continuing and lethal failure of Iraq's post-occupation authorities to establish the rule of law and protect their citizens."
In some cases, Human Rights Watch says it was told, Iraqi security forces had actually "colluded and joined in the killing".
Recently, posters appeared in Sadr City - a conservative, Shia area of Baghdad - calling on people to watch out for gay men and listing not only their names but also their addresses.
One gay man in Baghdad described the killing campaign as a witch-hunt.
Nearly 90 gay men have been killed in Iraq since the beginning of January and many more are missing, local gay rights campaigners say.
The report, called They want us exterminated: Murder, Torture, Sexual Orientation and Gender in Iraq, says horrifically mutilated bodies of gay men have been left on rubbish tips.
Sometimes their bodies are daubed with offensive terms such as "pervert", or "puppy" which is a hate word for gay men in Iraq.
The report contains detailed testimonies of a range of brutal treatment of gay Iraqi men.
"We've heard stories confirmed by doctors of men having their anuses glued and then being force-fed laxatives which leads to a very painful death," says Ms Moumneh told the BBC.
When questioned in the past, officials in Iraq have condemned the killings, but the BBC's Natalia Antelava in Baghdad reports that gay men there say nothing has been done to protect them.
"These killings will continue, because it has simply become normal in Iraq to kill gay men," said a gay Iraqi man who did not want to be named.
Mehdi army spokesmen and clerics have condemned what they call the "feminisation" of Iraqi men and have urged the military to take action against them.
The report said many gay men have fled to other countries in the region, despite consensual homosexual activity being illegal there, because the risk of victimisation is reduced.
HRW says the threats and abuses have spread from Baghdad to Kirkuk, Najaf and Basra, although persecution remains concentrated in the capital.
Officials say part of the problem in dealing with the attacks is that victims' relatives seldom if ever provide information to the police.
"They consider talking about the subject worse than the crime itself. This is the nature of our society," ministry spokesman Major General Abdul-Karim Khalaf said.