A senior Islamic State leader has been killed in an American raid in Syria, US Defence Secretary Ash Carter has said.

He told a news conference the militant, Haji Imam, also known as Abdul Rahman Mustafa al-Qaduli, was in charge of the group's financing.

Mr Carter also said the death of IS' military commander, Omar al-Shishani, had finally been confirmed after an airstrike this month.

US officials previously announced the death of the militant, also known as Omar the Chechen, but activists later claimed he had only been wounded.

Mr Carter refused to say whether al-Qaduli was killed by an airstrike or ground forces.

Two senior defence officials told Fox News a US special operations team killed al-Qaduli in a pre-dawn raid on Thursday in Syria.

Joined by the Chairman of the Joint Chiefs of Staff, General Joseph Dunford, Mr Carter said the death of al-Qaduli would hamper the group's operational ability.

According to the US Department of Justice, al-Qaduli joined al Qaeda in 2004 under the command of now-deceased al Qaeda in Iraq leader Abu Musab al-Zarqawi and became his deputy.

He joined Islamic State following his release from prison in early 2012 and travelled to Syria.

In May 2014, the US Department of the Treasury designated al-Qaduli a Specially Designated Global Terrorist.

The US government had placed a US$7m (€6.2m) bounty on his head.