Tuesday's pre-dawn attack on the camp began with a car bomb, followed by a furious firefight that is believed to have killed at least 10 Burundian soldiers and 20 Al Shabab terrorists.
Ten Burundian peacekeepers have been killed in an attack by Al Shabab terror group on an African Union (AU) base in Somalia.
Twenty-five soldiers were injured and five are missing, while 20 Al Shabab fighters were killed, Burundi's army said in a statement on Wednesday.
It was the first attack on a peacekeeping base since the AU Transition Mission in Somalia (ATMIS) replaced the previous AMISOM force on April 1.
AU forces sent in helicopter gunships after Tuesday's pre-dawn attack on a camp housing Burundian troops near Ceel Baraf, a village some 160 kilometres (100 miles) northeast of the capital Mogadishu.
A local military commander, Mohamed Ali, told AFP on Tuesday that the assault began with a car bomb before a furious firefight broke out.
A high-ranking Burundian military officer told AFP that 400 fighters stormed the base, forcing Burundian soldiers to retreat to a nearby hillside where they continued to fight, supported by drones and helicopters.
Al Shabab claimed responsibility for the attack, saying it had taken control of the camp and that 173 soldiers had been killed.
The Al Qaeda-linked group has been involved in a deadly armed conflict against Somalia's central government for more than a decade.
Somalia's government condemned the "heinous" attack and appealed to the international community to do more to support Somali forces and ATMIS "in effectively combatting terrorism".
AU Commission chief Moussa Faki Mahamat said on Twitter he spoke to Burundi's President, Evariste Ndayishimiye, to pay his respects for the "sacrifice" of the peacekeepers who lost their lives.
The United States, Britain and the regional bloc IGAD (Intergovernmental Authority on Development) condemned the attack, with the US embassy in Mogadishu vowing to "stand with ATMIS and Somalia's security forces..."
ATMIS — made up of troops from Burundi, Djibouti, Ethiopia, Kenya and Uganda — is tasked with helping Somali forces take primary responsibility for security in a country that has been mired in conflict since 1991.
Al Shabab controlled Mogadishu until 2011 when they were driven out by AU troops. But they still hold territory in the countryside and attack civilian, military and government targets in Mogadishu and elsewhere.