(CNN) -- A new United Nations report asserts that both sides in the Syrian civil war have committed grave crimes in violation of international law.
Government forces continue to attack civilian populations in what amounts to crimes against humanity, says the report, released Wednesday by the U.N. Human Rights Council.
But anti-government groups, in their fight against President Bashar al-Assad, have themselves committed war crimes, including murder, torture and hostage-taking, the report states.
The report provides details on nine massacres that it is investigating, eight believed to have been carried out by the government and one by the opposition.
As the fighting rages, "it is civilians who continue to pay the price for the failure to negotiate an end to this conflict," the agency said in a prepared statement.
The report comes as the international community grapples with how to respond to a chemical attack in Syria last month that was allegedly launched by the government.
Government blamed for al-Bayda massacre
One of the eight massacres the report attributes to government forces is a notorious event that occurred in the village of al-Bayda in May.
Some victims in al-Bayda "appeared to have been hit in the head with blunt, heavy objects," the report states. "Bodies of 30 women, also apparently executed, were found in a house not far from the centre while tens of bodies were strewn in the streets. Between 150-250 civilians were allegedly killed."
"There are reasonable grounds to believe that government forces and affiliated militia including the National Defence Forces are the perpetrators of the al-Bayda massacre," the report says.
Other massacres attributed to the government involved indiscriminate shelling of certain areas and the killing of civilians by snipers.
Unlawful killings by government forces also were reported at detention centers, where there was a spike of deaths of people in custody, the report says.
Shootings at checkpoints and snipers killing civilians in Damascus are also blamed on the government forces.
Jihadists linked to opposition abuses
The anti-government war crimes recorded in the U.N. report are mostly attributed to jihadist groups who joined the battlefield late but are now among the most powerful groups.
In June, anti-government forces, including members of the jihadist Jabhat al-Nusra, attacked the Shiite areas of the village of Hatla.
"There are reasonable grounds to believe that the anti-government fighters who attacked Hatla unlawfully killed at least 20 civilians in violation of international law," the report states.
The execution by anti-government forces of a 15-year-old boy accused of blasphemy is attributed to the Islamic State in Iraq and Syria. Another unlawful death recorded by the United Nations is that of a Catholic priest in Idlib. The priest was one of the few remaining Christians in a town where Jabhat al-Nusra operated, the report states.
'No military solution'
The U.N. report is based on 258 interviews conducted between May 15 and July 15.
"The perpetrators of these violations and crimes, on all sides, act in defiance of international law," the report states. "They do not fear accountability."
The period covered by the report precedes the date of the chemical attack in Syria that has brought the possibility of military strikes in response.
Both sides in the civil war continue to fight because they believe that a military victory is possible, the report states, but it asserts such an outcome is not possible.
"There is no military solution to this conflict," it says. "Those who supply arms create but an illusion of victory."