The death toll has risen from this week's suicide bombing in Mogadishu, Somalia, United Nations officials said Thursday.

More than 100 people are now reported dead after Islamic militants detonated a truck loaded with drums of fuel outside Somalia's Ministry of Education.

The blasts shattered more than a month of relative calm in Mogadishu. The al-Qaeda-linked militant group al-Shabab has claimed responsibility for the attack on one of its websites.

"Our Mujahideen fighters have entered a place where ministers and AMISOM foreigners stay," al-Shabab said in an online post.

They were referring to the Ugandan and Burundian forces that make up the African Union peacekeeping mission.

Tuesday's attack is the deadliest single bombing by al-Shabab. The group promised more attacks, saying they will be "back-to-back" and will "increase day by day."