'Chemical agent' traced in IS mortar fire, says US general
Tests on Islamic State mortar fragments from fighting in Iraq show traces of chemical arms, the US military says.
US Brig Gen Kevin Killea said they had found traces of chemical agent sulphur mustard on mortars used by IS to attack Kurdish forces in northern Iraq.
But he said the tests were not conclusive and final testing was due.
US officials have been looking into reports that IS used chemical weapon mustard gas in an attack earlier this month in the town of Makhmour.
IS has previously been accused of using chlorine gas against Kurdish fighters.
Mustard agent, or sulphur mustard - more commonly referred to as mustard gas - causes blistering of the skin, eyes and respiratory tract.
The mortar shell fragments undergoing tests were handed over by Kurdish forces from an attack on 11 August, Brig Gen Killea told reporters on Friday.
They had been fired at Kurdish Peshmerga positions near Makhmour, close to the city of Irbil.
"We were able to take the fragments from some of those mortar rounds and do a field test...on those fragments, and they showed the presence of HD, or what is known as sulphur mustard," Brig Gen Killea said.
He described sulphur mustard as a Class 1 chemical agent, one that is rarely used outside of chemical warfare.
US officials recently suggested IS may have obtained the mustard agent in neighbouring Syria, despite the Syrian government saying that all of its stockpiles of such weapons had been destroyed.
Former Iraqi leader Saddam Hussein also used weapons such as mustard agent against the Kurds and against Iran.
The US military announcement comes two years after US President Barack Obama issued a "red line" to Syrian President Bashar al-Assad over a chemical weapon attack in eastern Damascus that killed hundreds of civilians.
In a UN-backed deal that followed, Mr Assad handed over 1,180 tonnes of declared toxic agents and precursor chemicals to the Organisation for the Prohibition of Chemical Weapons (OPCW).