Cluster munitions have been banned by almost 120 countries because of the indiscriminate threat they pose to civilians.
The Syrian regime and its ally Russia have extensively used internationally banned cluster munitions in renewed air operations targeting opposition groups in Syria, Human Rights Watch (HRW) said on Thursday.
In a report released online, the New York-based rights group announced that it had documented 47 cluster munitions attacks since May 27.
More than 120 people were killed and at least 100 others wounded in these attacks.
Many of them took place north and west of Aleppo, as regime forces seek to besiege the opposition-controlled part of the strategically important northern city.
Russia/Syria: Widespread New Cluster Munition Use https://t.co/CfMLAJznAt— Human Rights Watch (@hrw) July 28, 2016
Cluster munitions explode in the air, distributing smaller bombs over a large area.
They are fired from the ground by artillery and rockets, or dropped from aircraft.
Cluster munitions are dangerous because they are inherently indiscriminate weapons. Most of them are free-falling which means that they are not guided towards a target.
Moreover, since the unexploded ones might explode when handled or disturbed, they continue to threaten civilians until they are cleared and destroyed.
From March 29 to June 2, two teams from Syria Civil Defense, a search-and-rescue volunteer group, cleared 615 submunitions in the provinces of Idlib and Hama alone.
The conflict in Syria, in which at least 280,000 people have been killed so far, erupted in March 2011 following a violent crackdown on anti-government protests across the country.
However, a significant increase in the number of cluster munition attacks has been recorded since last September when Russia began its military operations in the country.
Ole Solvang, HRW's deputy emergencies director, described the use of cluster munitions as "relentless" and called on all sides to stop.
"The Russian government should immediately ensure that neither its forces nor Syria's use this inherently indiscriminate weapon," Solvang said.
The Syrian regime and Russia are not signatory to the 2008 Convention on Cluster Munitions that bans the use of cluster munitions.
However, HRW says "they are still bound by international humanitarian law, or the laws of war, which prohibits indiscriminate attacks."