Russia on Sunday accused the United States of carrying out bombing using white phosphorous in eastern Syria against military targets in civilian areas, which is banned under international law. "Two American F-15 planes carried out bombings on September 8 (Saturday) targeting the area of Hajin in the Deir Ezzor region using incendiary phosphorous ammunition," Russian general Vladimir Savtchenko said in a statement.

"These strikes resulted in fierce fires. We are clarifying the information concerning possible deaths and injuries," he added. In Syria, the jihadist Islamic State group still controls a pocket in Deir Ezzor between the Euphrates River and the Iraqi border, and also remains in the vast Syrian desert. An international coalition led by the United States is helping a coalition of Kurdish and Arab fighters from the Syrian Democratic Forces (FDS) which for months have been conducting an offensive to oust IS.