A senior Islamic State (IS) group leader in Iraq and Syria has been killed in an operation by members of the Iraqi national intelligence service along with US-led coalition forces, the Iraqi prime minister has said.

Abdallah Makki Muslih al-Rifai, also known as Abu Khadijah, "was considered one of the most dangerous terrorists in Iraq and the world", according to Prime Minister Mohammed Shia al-Sudani, BBC reported.

US President Donald Trump said "he was relentlessly hunted down by our intrepid warfighters".

The US Central Command (CENTCOM) said it conducted a "precision airstrike" in Iraq's western Al Anbar province, which killed "one of the most important" IS members on Thursday.

Rifai was the head of IS's most senior decision-making body and was responsible for operations, logistics, and planning conducted by IS globally, the US Central Command said.

He also directed a large portion of finance for the group's global organization, CENTCOM added.