MOGADISHU (AFP) - US military forces launched air strikes against the leader of Somalia's Al-Qaeda-linked Al-Shebab, the government said on Tuesday, claiming "casualties" but with no details if the main target was killed.

"The Americans carried out a major air strike targeting a gathering by senior Al-Shebab officials, including their leader Abu-Zubayr," said Abdukadir Mohamed Nur, governor for southern Somalia's Lower Shabelle region.

Abu-Zubayr is the often used name for Shebab supreme commander Ahmed Abdi Godane, listed by the US State Department as one of the world's eight top terror fugitives.

The Pentagon have confirmed an "operation" was carried out.

"We are assessing the results of the operation and will provide additional information as and when appropriate," Pentagon Press Secretary Rear Admiral John Kirby said in a statement.

The air strike on Monday comes days after African Union (AU) troops and government forces launched a fresh offensive against Shebab strongholds aimed at seizing key ports, and cutting off an important source of revenue for the Islamist rebels.

Shebab fighters have largely fled in the face of the offensive that began on Friday, and Nur said the air strike was targeting Shebab commanders as they gathered for a meeting.

"They were meeting to discuss about the current offensive in the region," Nur said. "There were casualties inflicted on the militants, but we don't have details so far."

He said the strike hit a Shebab hideout used as a training camp for suicide bombers, in remote villages of the Lower Shabelle region, south of the capital.
Godane, 37, who was reportedly trained in Afghanistan with the Taleban, took over the leadership of the Shebab in 2008 after then chief Adan Hashi Ayro was killed by a US missile attack.

Al-Qaeda chief Ayman al-Zawahiri has recognised Godane as the head of the "mujahedeen" in East Africa, although letters released after Osama bin Laden's death show the late Saudi Islamist leader had lower regard for the Somali's abilities.

He is included in a third category of men on whom information warrants a US$7-million (S$8.74 million) reward, alongside Nigeria's Boko Haram leader. Tip-off on Taleban's Mullah

Omar is worth up to US$10 million, and Zawahiri, US $25 million.

The Shebab are fighting to topple Somalia's internationally-backed government, and regularly launch attacks against state targets, as well as in neighbouring countries that contribute to the AU force.

On Sunday, the Shebab carried out a car bomb and gun attack against an intelligence headquarters in the capital Mogadishu.