Human Rights Watch said on Monday that both Takfiri and western-backed opposition militants have indiscriminately targeted civilians in violation of the laws of war.

Human Rights Watch said on Monday that both Takfiri and western-backed opposition militants have indiscriminately targeted civilians in violation of the laws of war.

In a new report, the New York-based group said it had documented dozens of opposition attacks against civilians in government-held parts of Syria.

The group's deputy Middle East and North Africa director Nadim Houry said there had been a "race to the bottom in Syria, with rebel groups mimicking the ruthlessness of government forces."

"Civilians are paying the price, be it in government or rebel-held areas, with an inadequate international response," Houry said.

The group documented car bombings and indiscriminate shelling in government-held areas between January 2012 and April 2014, focusing mostly on areas investigators were able to visit.

The report said several dozen car bomb attacks in Damascus and Homs provinces had hit areas with no government military targets, and often targeted districts occupied by religious minorities.

"Besides being indiscriminate, many of these attacks seemed primarily intended to spread terror among the civilian population," the report said.

Among the worst of the bombings was an attack in October last year outside a school in the Akrameh neighborhood of central Homs city that killed more than 45 children.

HRW also documented regular indiscriminate shelling by opposition groups on the capital Damascus and Homs city, mostly against civilian areas, and in some cases schools full of children.

The groups responsible for the indiscriminate attacks ranged from Takfiris like the ISIL group to militants grouped under the Western-backed Free Syrian Army, the report said.