Al-Shabab fighters have attacked a military base housing Ugandan forces of the African Union peacekeeping mission in Somalia, according to the East African country’s contingent and a Somali captain.

The rebels attacked the base belonging to the African Union Transition Mission in Somalia (ATMIS) in Bulamarer, 130km (80 miles) southwest of the capital, Mogadishu, on Friday.

“There was an attack this morning at our base … by elements of al-Shabab but we are waiting for official communication from ATMIS headquarters,” said Uganda People’s Defence Force (UPDF) deputy spokesman Deo Akiiki.

ATMIS, which has 22,000 troops, was assessing the security situation, it said on Twitter, without providing details. The mission has been assisting Somalia’s federal government in its war against the al-Qaeda-linked armed group since 2022 when it replaced the AU Mission in Somalia (AMISOM).

Meanwhile, al-Shabab has claimed in a statement that it carried out suicide bomb attacks and killed 137 soldiers.

There was no immediate official confirmation of the casualties and the group tends to give figures that differ from those issued by the authorities.

A Somali captain who gave his name as Abdullahi told Reuters news agency from the Lower Shabelle region that the rebels attacked an ATMIS base and an adjacent one belonging to the Somali military.

“That prompted a fierce battle for hours. All groups including al-Shabab suffered heavy casualties,” he said, without giving further details.

Residents of the town said they woke up to the sound of huge explosions and heavy weapons. “Now we see al-Shabab in the town. We cannot know how many died. We are not hearing any shots from ATMIS and government now,” resident Rukia Farah said.

Since 2006, the group has been fighting to topple the government and establish its own rule based on its strict interpretation of Islamic law.

Last August, an intensive government offensive began after the election victory of President Hassan Sheikh Mohamud and has made significant gains in eroding the group’s control of vast swaths of land.

But al-Shabab is still capable of launching significant attacks on government, commercial and military targets. It also intermittently launches attacks in neighbouring Kenya as part of reprisals for Nairobi sending troops to support Mogadishu’s rebel pushback.