At least 10 Burundian peacekeepers were killed in Tuesday's attack by Al-Shabaab jihadists on an African Union (AU) base in Somalia, Burundi's army said Wednesday.
Twenty-five soldiers were injured and five are missing while 20 Al-Shabaab militants were killed, the army said in a statement.
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 the pre-dawn attack on a camp housing Burundian troops near Ceel Baraf, a village some 160 kilometres (100 miles) northeast of the capital Mogadishu, military officials and witnesses said.
A local military commander, Mohamed Ali, told AFP on Tuesday that the assault began with a car bombing before a furious firefight broke out.
Two Burundian military sources told AFP that 45 peacekeepers were reported as dead or missing, with 25 others injured.
"The provisional toll is 45 soldiers killed or missing, including a battalion commander colonel," a Burundian military source told AFP on condition of anonymity, while a second source backed up the figures.
Al-Shabaab claimed responsibility for the attack, saying it had taken control of the camp and that 173 soldiers had been killed.
The Al-Qaeda-linked Islamist militants have been waging a deadly insurgency against Somalia's fragile 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".
The bloodshed highlights the security woes in the troubled Horn of Africa country, which is also embroiled in a deep political crisis over delayed elections and faces the threat of famine.
Al-Shabaab fighters controlled Mogadishu until 2011 when they were driven out by AU troops.
But they still hold territory in the countryside and frequently attack civilian, military and government targets in Mogadishu and elsewhere.