Organisation for the Prohibition of Chemical Weapons chief Fernando Arias met Ukraine's parliamentary chairman Ruslan Stefanchuk to discuss "the implementation of the Chemical Weapons Convention," the Hague-based organisation said.

"Since the beginning of the current conflict, the OPCW Technical Secretariat has been closely monitoring the situation in Ukraine," the OPCW said in a statement after the meeting.

Friday's talks included "the threat of chemical weapons use and assistance and protection support from the OPCW Technical Secretariat as well as from States Parties to the convention," it said.

The Chemical Weapons Convention is the treaty signed by most countries around the world -- including Ukraine and Russia -- banning the use of chemical weapons.

Stefanchuk's visit comes in the wake of Russia's attack on a chemical plant last week in the eastern Ukrainian city of Severodonetsk in which a nitric acid tank was hit.

The destruction of the tank prompted Ukrainian authorities to call on residents to "stay indoors and prepare protective face masks impregnated with soda solution".

Arias said the OPCW was ready to provide technical assistance to Ukraine, "especially in the field of chemical safety and security."

Stefanchuk in turn said Ukraine -- which ratified the convention in 1998 -- remained committed to its implementation.

"Ukraine undertakes not to use any chemicals as means of warfare," Stefanchuk said.

The OPCW has 193 member states including Kyiv and Moscow, and has overseen the destruction of 99 percent of the world's declared chemical stockpiles.