Physicians for Human Rights was able to get a team of interviewers into the embattled city of Misrata from June 5-12, just after Libyan rebel forces expelled Gadhafi's loyalists.

Interviewing dozens of survivors of the two-month siege, the Boston-based PHR found widespread evidence of crimes against humanity and war crimes, including summary slayings, hostage-taking, rapes, beatings, and use of mosques, schools and marketplaces as weapons depots.

``Four eyewitnesses reported that (Gadhafi) troops forcibly detained 107 civilians and used them as human shields to guard military munitions from NATO attacks south of Misrata,'' said the report, which was released Tuesday.

``One father told PHR how (Gadhafi) soldiers forced his two young children to sit on a military tank and threatened the family: 'You'll stay here, and if NATO attacks us, you'll die, too.'''

PHR obtained copies of military orders as evidence that Gadhafi ordered his troops to starve civilians in Misrata, while pillaging food caches and barring locals from receiving humanitarian aid.

Rape was also ``a weapon of war,'' Richard Sollom, the lead author of PHR's report, told the Associated Press on Monday. While he said no one has evidence to prove that rape was widespread, the fear of it certainly was, he said.

And it had deadly consequences in the form of ``honor killings'' of rape victims by their shamed family members.

``One witness reported that (Gadhafi) forces transformed an elementary school into a detention site where they reportedly raped women and girls as young as 14 years old,'' the PHR report said. It added that it had found no evidence to confirm or deny reports that Gadhafi troops and loyalists were issued Viagra-type drugs to sustain their systematic rapes.

The school where the rapes were said to have taken place was in Tomina, near Misrata, PHR said.

In at least one instance, PHR reported, three sisters -- ages 15, 17 and 18 -- were raped at Tomina, and their father subsequently slit their throats as an ``honor killing'' to lift the shame from his family.

PHR also noted that ``some in Tomina have stood up against this practice, including a well-known sheik who has publicly advocated for raped women and girls to be seen as brave and bringing honor to their families.''

Physicians for Human Rights only investigated the abuses committed by Gadhafi forces. The timing of their visit, and its focus on Misrata, meant that PHR was not in a position to comment on allegations of rights violations by the Libyan rebels or by NATO, the group said.

However, PHR urged the rebel National Transitional Council to enforce law and order, suppress vigilantism, and hold all right violators responsible and prevent them from occupying positions of power.

It said NATO should investigate any credible claims made against the allied force that supported the rebels, largely through thousands of bombing sorties.

PHR particularly raised the issue of medical neutrality in war time, accusing the Gadhafi forces of attacking hospitals, clinics and ambulances, and preventing doctors from reaching or treating injured civilians.

Last week, the New York-based Human Rights Watch said it had collected evidence that ``strongly suggests that Gadhafi government forces went on a spate of arbitrary killing as Tripoli was falling.''

Meanwhile, Amnesty International, which is based in London, also accused pro-Gadhafi guards of raping child detainees, but added that Libyan rebels are abusing children and holding migrant workers as prisoners.

All three major human rights groups have called on both sides to respect prisoners -- and beyond that, to build a post-Gadhafi Libya.

``Individual perpetrators need to be brought to justice and held to account for their crimes,'' Sollom said. ``And as we've seen historically in places like South Africa and Bosnia and Rwanda, it's a cathartic experience for the country, and a necessary one, to move forward.''