At least 20 people have been killed and dozens others injured in fresh clashes between Somali government and the insurgent groups, Al-Shabaab that rocked Somalia's capital, Mogadishu, Radio Garowe reports.

Gun battles and shelling rocked Mogadishu's northern districts of Bondhere and Hawlwadag, where African Union troops attacked rebel positions.

"Somali government troops attacked the rebel militias and we killed 20 Al-Shabaab members including foreigners, the insurgent officers and militias defected to us and we will show the media soon," said a government official, Abdirizak Qaylow

On the other hand, Somalia's Al-shabaab spokesman, Abdi Aziiz Abu Mus'ab denies the statement from the Somali government and he said no fighter from his side was killed.

"We repelled their attacks and forced them back, no fighter from our side was killed in the clashes," said Abdi Aziiz Abu Mus'ab, a spokesman for al-Shabaab fighters.

The fresh clashes happened as more than 25 people were killed Thursday on a suicide bomb attack on Mogadishu's airport. Somali civilians and African peacekeeepers were among the dead.

Al-Shabab is fighting to overthrow the government and install its own radical interpretation of Islamic law. The group control large parts of the country, while the government holds only small parts of Mogadishu.