US officials say they have killed Bilal al-Sudani, a key regional leader of the Islamic State group, in a special military operation ordered by President Joe Biden.

Al-Sudani was killed during a gunfight after US troops descended on a mountainous cave complex in northern Somalia, US officials announced on Thursday.

Around 10 of al-Sudani Islamic State (IS) associates at the scene were killed, but there were no American casualties, the officials said.

"Al-Sudani was responsible for fostering the growing presence of [IS] in Africa and for funding the group's operations worldwide, including in Afghanistan," said US Secretary of Defence LLoyd Austin.

Wednesday's raid "leaves the United States and its partners safer and more secure, and it reflects our steadfast commitment to protecting Americans from the threat of terrorism at home and abroad", Austin said in a statement.

Important target

Al-Sudani had been on the US intelligence radar for years.

US officials told media that al-Sudani had provided and coordinated funding for branches of IS from his mountain base in northern Somalia - not only in Africa, but also Islamic-State Khorasan, the arm operating in Afghanistan.

Ten years ago, before he joined IS, al-Sudani was involved in recruiting and training fighters for the extremist al-Shabaab movement in Somalia.

"Al-Sudani had a key operational and financial role with specialised skills which made him an important target for US counterterrorism action," the official said.

Officials provided few details about how the operation was carried out or the circumstances surrounding al-Sudani's killing.

One said that US forces had intended to capture al-Sudani but that did not prove to be "feasible" as the operation was carried out.

Al-Shabaab

The operation comes days after Africa Command said it had conducted a collective self-defence strike northeast of Mogadishu, the capital, near Galcad.

In that incident, Somalia National Army forces were engaged in heavy fighting following an extended and intense attack by more than 100 al-Shabaab fighters.

The US estimated approximately 30 al-Shabaab fighters were killed in that operation.

The offensive has been described as the most significant in more than a decade.

(with wires)