A massive truck bomb kills at least 70 people outside government buildings in the centre of Somalia's capital, Mogadishu. Al-Shabaab fighters have claimed responsibility.

Please wait while this video loads. If it doesn't load after a few seconds you may need to have Adobe Flash installed.

The blast occurred outside a compound of four government ministries where students had gathered to take exams. Emergency services said they had moved 70 dead bodies and were treating around 50 people for injuries, mostly burns.

The compound is under control of the government forces and African Union peacekeeping troops. Police were seen evacuating students from nearby buildings damaged by the blast.

One witness said it looked as though the truck had been packed with petrol and explosives. He said students, soldiers and civilians were among the dead.

The al-Qaeda-linked fighters threatened to carry out attacks on government installations after pulling most of their fighters out of Mogadishu in early August.

"Al-Shabaab carried out that attack," a spokesman for the insurgents told Reuters. "Our target was the ministries."

The Islamist militant group withdrew its forces from Mogadishu at the start of August. It has been fighting the western-backed government for four years and controls large parts of central and southern Somalia.

Somalia has also been suffering from the harsh drought and famine blighting its southern borders around the Horn of Africa. It is feared one in 10 of children in Somalia could starve to death. The security fears in the south have made it particularly difficult for aid agencies to deal with the crisis. Earlier in September Al-Shabab fighters allowed aid workers into their controlled parts of the control, which highlighted the severity of the crisis.

Channel 4 News reported last week that some women fleeing the drought claim they have been raped in the refugee camps in Mogadishu.