* Gaddafi's envoy on verbal offensive at UN rights forum
* Accuses rebels of cutting throats, mutilation, cannibalism
* Denies UN report which found war crimes by Gaddafi forces
* Head of UN inquiry dismisses widespread rape allegations (Updates with speeches, Bassiouni news conference)
By Stephanie Nebehay
GENEVA, June 9 (Reuters) - Libya on Thursday accused rebels of butchery and cannibalism, and NATO forces of war crimes, while firmly denying a United Nations report which found that its own troops had carried out murders, torture and abductions.
Mustafa Shaban, a Libyan foreign ministry official, delivered the attack and the defence of the government of Muammar Gaddafi at the U.N. Human Rights Council in Geneva.
The 47-member forum held a debate on a U.N. investigation which concluded last week that Gaddafi's forces committed war crimes and crimes against humanity. The team also found some evidence of crimes by opposition forces seeking to topple him.
An estimated 10,000 to 15,000 people have been killed in four months of fighting, leaving Libyans deeply scarred, according to the Cherif Bassiouni who led the three-member panel that visited Tripoli and rebel-held areas in late April. The estimates came from both government and rebel forces, he said.
"Cities in the hands of armed gangs suffer terrible violations of human rights and heinous crimes," Shaban said.
"In Misrata, Libyan and foreign gangs who were arrested confessed to cutting throats and cutting off breasts of live women and even admitted to acts of cannibalism.
"NATO is violating human rights in Libya tantamount to crimes against humanity, crimes of war and crimes of aggression," Shaban said in speech in which he later accused NATO of targeting civilians and civilian infrastructure.
But Britain's ambassador Peter Gooderham, whose country is helping to enforce NATO's no-fly zone, rejected his allegations.
Russia's envoy Valery Loshchinin called for further probing of "disproportionate actions" by NATO, adding: "There are more than enough witnesses to such actions".
NATO air strikes on Tripoli this week have been among the heaviest since bombing began in March. Government troops made an advance on the rebel-held western city of Misrata on Wednesday, shelling it and killing at least 12 rebels.
"I understand that the Libyan government is now claiming that the recent bombing caused casualties and destruction of property. It is possible. When we go back there, we'll take a look at that and determine whether that is the case," the Egyptian-born Bassiouni told a news conference.
"Concerning cannibalism, we've never heard about such a thing," he added.
It had found evidence of war crimes by Gaddafi forces, including attacks on civilians, aid workers, and medical units. Aircraft, tanks, artillery, Grad rockets snipers were used, he said. It found some evidence of crimes by opposition forces.
"Because it is a tribal society, anybody who gets killed has 300 relatives and friends who feel it," Bassiouni said.
International Criminal Court investigators have evidence linking Gaddafi to a policy of raping opponents and may bring separate charges on the issue, the ICC prosecutor Luis Moreno-Ocampo said in New York on Wednesday.
Bassiouni said that both sides had accused the other of deploying fighters armed with drugs to combat impotency to carry out rapes, creating a "massive hysteria".
His team uncovered only four alleged cases of rape -- Eman Al-Obaidi who claimed she was gang-raped by pro-government militiamen and three women in Misrata who said they had been sexually abused.
"Can we draw a conclusion that there is a systematic policy of rape? In my opinion we can't," Bassiouni said. "For the time being, the numbers are very limited. They've had a tremendous socio-psychological impact on society."
Bassiouni, professor of law emeritus at DePaul University College of Law in Chicago, had harsh words for world powers.
"This is a regime which for the last 40 years has supported all sorts of terrorist activities and subversive regimes which have resulted in killings of hundreds of innocent civilians in all sorts of different contexts.
"And yet that regime has sort of gotten a pass. It acquired respectability because it had the resources to do so. For the Colonel to believe he can get away with anything and buy his way out of it as he has in the past is quite logical in his mind." (Editing by Myra MacDonald)