PARIS — Syrian military forces have moved aggressively to retake territory lost to the insurgency in the country’s south over the past few days, antigovernment activists reported Thursday, and in one contested town at least 60 civilians, including women and children, were killed in what the opposition called a government-ordered atrocity motivated by revenge.
The reported massacre, which could not be independently verified, took place in Sanamayn, about halfway between Damascus and the southern city of Daraa. The town is at a vital highway that rebel forces have been fighting to control.
Brigades affiliated with the Free Syrian Army had seized several towns south of Sanamayn, and this month took control of a military base near Daraa, where the uprising against President Bashar Assad began more than two years ago.
The Syrian Observatory for Human Rights, an anti-Assad group based in Britain with a network of contacts inside Syria, said military forces had started the assault against Sanamayn on Wednesday, shelling and shooting randomly and burning or wrecking at least 20 houses. Victims included at least seven women and five children, the group said.
An anti-Assad activist reached independently by telephone who identified himself only by one name, Qaysar, for safety reasons, said some victims had been ‘‘summarily executed or stabbed or burned.’’ He said Sanamayn’s residents included displaced families uprooted by the civil war mayhem that has afflicted other parts of Syria, including some Damascus suburbs. As of Thursday he said, the town remained encircled by government forces.
Syria’s main political opposition group, the National Coalition for Syrian Revolutionary and Opposition Forces, described the reported killings in Sanamayn as a massacre by a military that ‘‘slaughters civilians in retaliation for its defeats.’’
The statement, issued from its Cairo headquarters, said the killings were committed ‘‘for no other reason than to satisfy the hunger for killing and the thirst for blood which control the ... criminal Assad regime.’’
There was no reporting about Sanamayn in Syria’s state-run media. Both sides have increasingly accused each other of atrocities in the conflict, which by UN calculations has left more than 70,000 people dead. Prominent human rights advocacy groups have contended that most of the killings are committed by government forces, which are increasingly using heavy weapons and warplanes.
One of those groups, Human Rights Watch, accused the Syrian authorities of war crimes Thursday in the ordering of indiscriminate and in some cases deliberate airstrikes against civilians.
The targets included hospitals and bakeries where civilians were standing in line for bread, the group said.
But it also castigated the Free Syrian Army, and other armed adversaries of the Assad government, saying insurgents did not take sufficient care to avoid deploying forces and setting up headquarters in or near densely populated areas.
“An attacking party is not relieved from the obligation to take into account the risk to civilians from an attack on the grounds that the defending party has located military targets within or near populated areas,’’ Human Rights Watch said.
The group, which is based in New York, said the airstrikes, constituted ‘‘serious violations’’ of international humanitarian law.
‘‘People who commit such violations with criminal intent are responsible for war crimes,’’ said the 80-page report, titled ‘‘Death From the Skies.’’