The al Qaeda-linked militants said they were behind a shooting rampage in a hotel on Tuesday that killed at least 33 people including members of parliament.

One military officer said the insurgents attacked government troops based near Villa Somalia, the presidential palace, in large numbers but were outgunned by the African Union's (AU) AMISOM peacekeeping force.

"They came close tonight but behind us are AMISOM tanks and at last we drove them away," army officer Issa Ali, who had been fighting in the frontline overnight, told Reuters.

Residents said bursts of automatic gunfire and the thuds of mortars could still be heard early on Wednesday morning.

"At least 83 people have died in the last three days, including the hotel blast, and 163 others were wounded," Ali Muse, the coordinator of ambulance service told Reuters.

Tuesday night's fighting was centred on the government-controlled neighbourhoods of Hodan and Wardhiglry. Al Shabaab and a second militant group, Hizbul Islam, control much of the capital, hemming President Sheikh Sharif's beleaguered government into just a few blocks.