Islamist Al-Shabaab fighters attacked an African Union military base in Somalia on Friday, the AU force said, without specifying if there were any casualties.
The Al-Qaeda-linked jihadist group has been waging a jihadist insurgency against the central government in the fragile Horn of Africa nation for more than 15 years.
The army base in Bulo Marer, 120 kilometres (75 miles) southwest of the capital Mogadishu "came under Al-Shabaab attack," the AU force known as ATMIS said in a statement on Facebook and Twitter.
"ATMIS forces are currently assessing the security situation," it said, without giving details.
The attack targeted Ugandan soldiers stationed in Somalia as part of ATMIS, Uganda Peoples' Defence Forces spokesman Felix Kulayigye said in a statement, adding they were "cross checking" details.
The 20,000-strong ATMIS force has a more offensive remit than its predecessor known as AMISOM.
The force is drawn from Uganda, Burundi, Djibouti, Ethiopia and Kenya, with troops deployed in southern and central Somalia.
Its goal is to hand over security responsibilities to Somalia's army and police by 2024.
Al-Shabaab claimed responsibility for Friday's attack via its communication channels, claiming it had overrun the base.
But Somali military commander Mohamed Yerow Hassan said the attackers had been repelled and the "situation is back to normal now."
"A suicide bomber drove a vehicle with explosives targeting the ATMIS base and then gunfire broke out," Hassan told AFP by telephone.
"The terrorists were forced to retreat and flee."
Attacks on army bases in isolated parts of Somalia are difficult to independently verify.
Al-Shabaab is known to exaggerate claims of battlefield gains in propaganda, while the governments of nations contributing troops to the AU force rarely confirm casualties.
Last year, Somalia's President Hassan Sheikh Mohamud launched an "all-out war" on the militants, rallying Somalis to help flush out members of the jihadist group he described as "bedbugs".
In recent months, the army and militias known as "macawisley" have retaken swathes of territory in the centre of the troubled country in an operation backed by ATMIS and US air strikes.
The US Africa Command on Monday said it had carried out a strike the weekend prior in Jilib in Somalia's south, and that initial assessments indicated no civilians were harmed.
Despite the gains by the pro-government forces, the militants have continued to strike with lethal force against civilian and military targets.
In the deadliest Al-Shabaab attack since the offensive was launched last year, 121 people were killed in October by two car bombings at the education ministry in Mogadishu.
In a report to the UN Security Council in February, UN chief Antonio Guterres said that 2022 was the deadliest year for civilians in Somalia since 2017, largely as a result of Al-Shabaab attacks.