Al-Shabaab said it launched a car bomb attack on a key military base manned by Somali and US troops on the outskirts of Kismayo, a port city in southern Somalia on Monday.

Heavy gunfight erupted following the explosion, said an army officer, who spoke to Radio Shabelle over the phone.

He added that the troops have fought off the attackers attempted to storm the base after blasting their way with the car bomb.

In a statement, Al-Shabaab claimed it killed at least 16 soldiers, including 4 US personnel, and wounding 12 others in the attack, which comes amid military pressure on the group.