The German government has said specialist laboratories in France and Sweden have confirmed Russian opposition leader Alexei Navalny was poisoned with the Soviet-era nerve agent Novichok.

A German military laboratory previously confirmed the substance was present in his samples.

German government spokesman Steffen Seibert said the Organisation for the Prohibition of Chemical Weapons has also received samples and is taking steps to have those tested at its reference laboratories.

Mr Navalny fell ill on a Russian domestic flight on August 20.

He was transferred to Germany two days later, where he has remained in hospital.