The world's chemical weapons watchdog said today it had again found traces of tear gas, which is banned as a weapon of war, on the battlefield with Russia in the Ukrainian region of Dnipropetrovsk.

Riot control agents such as tear gas are prohibited as a method of warfare under the Chemical Weapons Convention, a non-proliferation treaty overseen by the Organization for the Prohibition of Chemical Weapons (OPCW).OPCW).

The evidence was also found last year. Ukraine asked the agency for help, which sent its own team. Although the team does not have the authority to find Russia guilty, Ukraine and the United States have said that Russia illegally used tear gas to clear the camps.

Tear gas is not deadly, but it causes temporary irritation of the eyes and respiratory system.