More than 20 people have been killed after militants detonated a bomb and stormed into a beachfront hotel and restaurant in Somalia's capital Mogadishu.

Blasts and bursts of gunfire could be heard at the complex on the city's Lido beach on Thursday night as security forces ended the siege just before dawn.

The Al-Qaeda-linked group al-Shabaab has since claimed responsibility for the attack on its radio station - reporting that its fighters armed with AK-47 rifles and wearing suicide vests had invaded the hotel.

Government spokesman Abdisalam Aato confirmed all the attackers had been killed and that the authorities were checking every room and going through neighboring houses.

"This is a barbaric act and we condemn this act," he said. "Al-Shabaab is trying to disrupt the peace and Somalis will not stand for it. We will not be intimidated."

In a Twitter post, Prime Minister Omar Abdirashid Ali Sharmarke wrote, "I unreservedly condemn the barbaric attack @ Liido. My thoughts and prayers are with the victims."

I unreservedly condemn the barbaric attack @ Liido. My thoughts and prayers are with the victims #Somalia

— @SomaliPM (@SomaliPM) January 21, 2016