Gunmen are attacking a hotel in central Mogadishu following a car bombing at the entrance, according to witnesses and Somali police, with Al Shabaab group claiming responsibility.

Somali soldiers surrounded the Hotel Afrik and blocked off access to it, an AFP journalist reported.

The hotel is near the road leading to Mogadishu's airport, frequented by officials, members of the security forces and community leaders.

"There is ongoing [an] attack on a hotel... A car bomb hit the front entrance and armed men stormed the building," police officer Mohamed Adan told AFP.

"There is exchange of gunfire and the security forces are trying to rescue people inside from the attackers,” he added.

Witnesses confirmed a massive explosion followed by smoke after a car struck the hotel entrance at great speed, followed by gunfire.

"The gunfire is still going on and there was another blast after the first big one,” said Osman Saadaq, a witness.

Another witness, Muhubo Said, said "casualties could be possibly high”.

Al Shabaab claimed responsibility for the attack in a brief statement, saying: "The mujahidin stormed in an ongoing operation inside Hotel Afrik where members of the apostate team are stationed.”

The Al Qaeda-linked group has been waging a violent insurgency across Somalia seeking to unseat the internationally backed government in Mogadishu.

They were driven out of Mogadishu by government forces backed by 20,000 African Union peacekeepers in 2011.

But the group still controls swathes of territory outside the cities, from where they launch attacks against government targets, as well as occasionally crossing the border to carry out raids in Kenya.

Al Shabaab has ramped up the intensity of its attacks in Kenya in recent years, including several major assaults as far as the capital Nairobi, which have left nearly 300 dead.

Somalia was scheduled to hold indirect parliamentary and presidential elections before February 8 but the process has been derailed by political disagreements between the central government in Mogadishu and its federal states.