Kenyan fighter jets have bombed bases of Somalia's Al-Qaeda-linked Shabaab with scores of fighters killed, the African Union force said Monday.

The air strikes on the impoverished villages of Anole and Kuday in the southern Lower Juba region are part of the offensive by the 22,000-strong UN-backed AU mission in Somalia (AMISOM), who launched in March a fresh bid to wrest remaining towns from the Islamists.

"AMISOM forces have conducted airstrikes... as part of a sustained effort to destroy Al-Shabaab's military capabilities," the force said in a statement, adding it was Kenyan air planes that carried out the bombing.

Al-Shabaab spokesman Abdulaziz Abu Musab said Kenyan troops with the AU were also fighting the Islamists on the ground Monday, with jets and attack helicopters firing in support. The air strikes come one week after Al-Shabaab claimed responsibility for twin massacres on Kenya's coast in which over 60 people were killed, although Nairobi blamed those attacks on local political networks.

The militant group said it carried out the attacks in revenge for Kenya's military role in southern Somalia, as part of the AMISOM force.

At Anole, the AU said airstrikes "left more than 30 Al-Shabaab fighters dead", while in Kuday, the strikes "killed more than 50 insurgents." It was not possible to independently verify the numbers reported killed.

But Al-Shabaab boasted of having ambushed a Kenyan army convoy inside Somalia. "Several Kenyan soldiers were killed and their bodies are lying in the battle zone," Musab told AFP.
"Kenya's army is using helicopters and fighters jets to rescue their surrounded troops."

After withdrawing from fixed positions in the capital Mogadishu nearly three years ago, Al-Shabaab have lost most large towns to the AU and government soldiers. However, they still regularly launch guerrilla raids.

AU envoy Mahamat Saleh Annadif praised the latest push against the Islamist fighters. "We will employ all the means at our disposal to end their reign of terror," Annadif said.

Recent Al-Shabab attacks in Somalia have targeted key areas of government, or the security forces, in an apparent bid to discredit claims by the authorities and AU troops that they are winning the war.

Foreign diplomats say the group threatens several nations in East Africa, including Djibouti, Ethiopia, Kenya and Uganda, who all have troops in Somalia.