Syrian rebel groups have locked people in cages and driven them to areas near Damascus to use as human shields against heavy government air raids.
A video posted online by the Shaam News Network, an opposition media outlet, showed prisoners in iron cages being driven on the back of pick-up trucks through what it said was the area of Eastern Ghouta, northeast of the capital.
It does not help the opposition's cause for them to stoop to the same level as Assad by engaging in other kinds of war crimes.
The prisoners are believed to be officers and their families from the Alawite sect.
"After what happened in the city of Douma and the whole of eastern Ghouta, most people decided to place those prisoners from the Alawite sect and high-ranking regime officers in cages so they can taste our misery," said Bara Abdul Rahman, a media activist in the video.
Douma is regularly targeted by government air strikes. A medical centre run by Doctors Without Borders (MSF) was bombed on Friday killing 70 and leaving at least 550 wounded.
Meanwhile, UN special envoy to Syria, Staffan de Mistura, has said that he believed the Syrian government and representatives of the opposition should be involved in the working groups in the follow up of the Vienna talks.
In August, more than 100 people were killed in Douma, an opposition stronghold, as the fighting intensified amid efforts to find a political solution.
"I think it is important for us to understand the background. Douma and broader Eastern Ghouta are under siege by Syrian regime for some three years," said Kenneth Roth, executive director for Human Rights Watch.
"With rare exceptions it's impossible to get food and other necessities in. People at times have resorted to eating grass just to survive," Roth told Al Jazeera from New York.
The Syrian military and air force, meanwhile, have continued with heavy bombardments.
A video posted on social media shows the aftermath of shelling in Douma by what is believed to be Syrian forces, as civilians run for cover. Al Jazeera could not verify the authenticity of the footage.
There have also been numerous explosions in the southern town of Deraa, with military helicopters allegedly dropping barrel bombs across a number of suburbs.
"What we are seeing here is war crimes committed by both sides. Siege of civilians and indiscriminate bombardment of civilian areas by Assad regime is a classic war crime," Roth said.
"What's important under the law that war crimes by one side is not justifiable by another group," he said.
"It does not help the opposition's cause for them to stoop to the same level as Assad by engaging in other kinds of war crimes."
On Monday, Russia's defence ministry spokesperson said the country's air force hit 237 targets in Syria in the last two days, Reuters reported.
"In the past 24 hours 131 sorties have been carried out from Hmeymim airbase, hitting 237 terrorist targets in the provinces of Hama, Latakia, Homs, Damascus, Aleppo and Raqqa," Igor Lonashenkov, the Russian Defence Ministry spokesperson, said.
Suspected Russian warplanes also bombed the outskirts of the strategic city of Palmyra held by the Islamic State of Iraq and the Levant, on Monday, activists said.
Source: Al Jazeera