Russian Foreign Minister Sergei Lavrov denied information from the leading human rights organization that Syrian authorities used Russian-made cluster bombs against rebels.

The New York-based Human Rights Watch (HRW) said earlier that during the ongoing conflict in Syria Russian-made RBK-250 series cluster bomb canisters with AO-1SCh fragmentation bomblets were used by the government troops against the rebel forces.

“There is no confirmation to this… There are loads of weapons in this region, including in Syria and other countries of the region, and arms are supplied there in large quantities and illegally,” Lavrov said.

He also said that “it is very difficult to establish from where and how ammunition and weapons are supplied there.”

Seventy seven countries signed a convention in 2008 to ban the use of cluster bombs, which were actively used by the United States during a 1999 military campaign in Yugoslavia. However, Syria, as well as Russia, the United States and China did not sign the convention.

The Syrian conflict has claimed tens of thousands of lives, according to various Syrian opposition groups. The UN puts the death toll at over 20,000 people.