BEIRUT — The Kremlin on Tuesday dismissed the White House’s warning that the Syrian government is preparing a new chemical attack and that President Bashar al-Assad and his military ‘‘will pay a heavy price’’ if it goes ahead.
‘‘Such threats to Syria’s legitimate leaders are unacceptable,” said Dimtry Peskov, spokesman for Russian President Vladimir Putin.
Russia is Assad’s key backer, and it sided with him when he denied responsibility for an April 4 chemical weapons attack that killed dozens of people in Idlib province.
Days later, President Trump ordered a retaliatory cruise missile strike on a Syrian government-controlled air base.
Peskov criticized the Trump administration for using the phrase ‘‘another chemical weapons attack,’’ arguing that an independent investigation into the April attack was never conducted despite Russia’s calls for one.
Also, Syrian activists said an airstrike targeting an Islamic State-run jail in eastern Syria killed at least 42 prisoners.
The Britain-based Syrian Observatory for Human Rights said at least 15 Islamic State jailers and fighters also were killed in Monday’s airstrike, which happened in Deir El-Zour province.
Activist-run Deir Ezzor 24 said at least 60 civilians were killed. It said the building belonged to an Al Qaeda-linked commander before it was seized by the IS group in 2014.
The groups said the US-led coalition was behind the strike. It was not clear how they identified the aircraft responsible. The coalition could not immediately be reached for comment.
In addition to the coalition, Russia and Syria often carry out airstrikes against Islamic State in eastern Syria.