Washington: A US-led coalition air strike on Islamic State has killed a chemical weapons specialist who gained expertise under Saddam Hussein's regime.

US military officials say the air raid, carried out last Saturday near Mosul in Iraq, took out Abu Malik, whose training "provided the terrorist group with expertise to pursue a chemical weapons capability", the military said in a statement.

Malik had worked at a chemical weapons production plant under Saddam's regime and later forged an affiliation with al-Qaeda in Iraq in 2005, before joining IS, according to Central Command.

"His death is expected to temporarily degrade and disrupt the terrorist network and diminish ISIL's [Islamic State of Iraq and the Levant] ability to potentially produce and use chemical weapons against innocent people," it said.

There has been no sign IS possesses a major chemical weapons arsenal. But there have been allegations the jihadists have employed chlorine gas, which is classified as a "choking agent", though not as lethal as nerve agents.