Somalia's national security minister has resigned after an attack by al-Shabab fighters on the country's parliament.

The resignation of Abdikarim Guled late on Saturday came after the group set off powerful car bombs outside parliament and fighters armed with explosive vests, grenades and machine guns stormed into the building while scores of politicians were meeting.

"You are aware of the cowardly attack that the violent elements carried out on the parliament. I extend my condolences to the families of the deceased...Considering the current situation of the country, I officially hereby announce my resignation," Guled said.