BRUSSELS (AP) — The U.S. and Western powers have clashed with Russia and others at the global chemical weapons watchdog over a new investigative team being set up to apportion blame for poison gas and nerve agent attacks.

Russia said the new team would wield unlawful powers within the Organization for the Prohibition of Chemical Weapons and on Monday called for an "expert group" to assess the viability of such a team, something the U.S. insisted would hamstring the development of the team. The U.K. ambassador to the OPCW said that the Russian move would "undermine" plans to set up the team.

Britain has accused Russia of using a nerve agent in the attempted assassination in March in the English city of Salisbury of former spy Sergei Skripal. Moscow denies any involvement.