The UN human rights office said on March 11 that it had received "credible reports" of several cases of Russian forces using cluster bombs in Ukraine, adding that indiscriminate use of such weapons might amount to war crimes.
"Due to their wide area effects, the use of cluster munitions in populated areas is incompatible with the international humanitarian law principles governing the conduct of hostilities," UN spokesperson Liz Throssell told journalists in Geneva.
"We remind the Russian authorities that directing attacks against civilians and civilian objects, as well as so-called area bombardment in towns and villages and other forms of indiscriminate attacks, are prohibited under international law and may amount to war crimes," she added.
Earlier this month, NATO Secretary-General Jens Stoltenberg said that the alliance had also seen the use of cluster bombs in Ukraine.
Cluster bombs are made up of a hollow shell that explodes in mid-air, dispersing dozens or even hundreds of smaller bomblets over a wide area.
Russia is not a party to a 2008 convention banning cluster munitions, although it is bound by international humanitarian law, particularly the prohibition of indiscriminate attacks.