Arms Division Director for Human Rights Watch Steve Goose said his organization has identified 119 locations in Syria hit by cluster bombs in the last six months. Recent attacks on suspected civilian targets near Homs have left at least 11 people dead.
"Syria is expanding its relentless use of cluster munitions, a banned weapon and civilians are paying the price with their lives and limbs," he said in a statement.
Syria's civil war enters its third year this month. The United Nations estimates that at least 70,000 people have died and another 1 million have been displaced as a result of the conflict.
The rights organization identified some of the munitions as Soviet- and Egyptian-made bomblets.
"All nations that have joined the treaty banning cluster bombs have a legal obligation to speak out and condemn Syria's ever-expanding use of these indiscriminate weapons, yet too few are doing so," Goose said from New York.
Last week, British and French ministers said they were seeking concessions on an arms embargo on Syrian to help rebel forces fight government supporters. The British government said it was ready to send non-lethal military assistance to rebel forces on the ground.