Story highlights

NEW: Russia says the Human Rights Watch report is "another piece of disinformation"

One airstrike is reported to have killed 46 members of an extended family

The U.S.-led coalition has also faced accusations of bombing civilians

CNN  — 

Airstrikes believed to have been carried out by Russian warplanes in western Syria are reported to have killed dozens of civilians, Human Rights Watch says, suggesting that the bombings appear to be war crimes.

The aerial attacks took place in the northern part of Homs governate on October 15 as Russian and Syrian planes were supporting a ground offensive by the Syrian military and its allies against rebel groups, the rights group said in a statement Sunday.

Russian forces have faced a series of allegations of striking civilian areas since they began bombing parts of Syria last month in an effort to bolster the regime of Syrian President Bashar al-Assad, a close ally of Moscow. The Syrian American Medical Society has accused Russian warplanes of repeatedly targeting hospitals.

Russia has strongly denied such claims, saying it isn’t targeting civilians during its military operations inside Syria. And CNN is unable to independently verify the allegations.

The Human Rights Watch statement Sunday about the bombings in Homs earlier this month adds yet more accusations to the growing list.

“Indiscriminate or disproportionate attacks are serious violations of the laws of war that Russia has an obligation to investigate,” the statement said.

The Russian Foreign Ministry called the Human Rights Watch report “another piece of disinformation.”

Extended family reportedly killed

The deadliest airstrike in Homs was reported to have hit a house in the village of Ghantou, killing 46 members of an extended family, the rights group said, citing first responders and local activists.

Another airstrike hit near a bakery in the town of Ter Maaleh, reportedly killing 13 civilians and a local commander of the opposition Free Syrian Army, according to witnesses cited by Human Rights Watch.

The group said local residents told it they believe “the strikes were by Russian forces because the sound of the planes was different from the sound made by Syrian air force planes, and the Russians fly much higher.”

It cited a report by a pro-government radio station from Homs on the day of the bombings as saying that “joint Russian and Syrian” airstrikes hit opposition positions in Ghantou, Ter Maaleh and other areas.

But the Russian Foreign Ministry said there was nothing in the Human Rights Watch report that proved Russian forces were in the area at the time.

Accusations against U.S.-led coalition

The U.S.-led coalition that is carrying out a bombing campaign against ISIS in Syria and Iraq has also been accused of killing civilians.

Human Rights Watch in September 2014 called for an investigation into apparent U.S. missile strikes in northwestern Syria that it said were reported by local residents to have killed at least seven civilians. The Pentagon had said at the time that the military was looking into claims of civilian casualties but hadn’t found any proof to support them so far.

The Syrian Observatory for Human Rights, a pro-opposition group based in London that monitors the conflict, reported in May that coalition airstrikes had killed more than 50 civilians near the city of Aleppo.

The U.S. military vowed to investigate the report. U.S. Central Command said at the time that coalition forces had carried out airstrikes in the area. But it said it had no indication that any civilians were killed in those strikes.

CNN’s Nic Robertson and Alla Eshchenko contributed to this report.