The US military says the leader of the Islamic State militant group has been killed in an operation in Syria.

The US Central Command said in a statement on Wednesday that Abu al-Hasan al-Hashimi al-Qurashi was killed in mid-October in southern Syria. It said the operation was conducted by the Free Syrian Army. The anti-government group is supported by the US and others.

White House Press Secretary Karine Jean-Pierre said in a news conference that the US was "pleased" to see the removal of the top ISIS leader. She went on to say, "The United States remains committed to countering the global threat from ISIS."

The group's previous leader blew himself up during a raid by American forces in northwestern Syria in February. ISIS announced Abu al-Hasan al-Hashimi al-Qurashi as his successor in March.

ISIS lost control of areas in Syria and Iraq, but has continued to carry out terrorist attacks. It is unclear whether the death of the group's leader will put an end to its terrorist activities.