A CAR bomb has torn through a government compound in Mogadishu, killing more than 70 people in the deadliest attack by Somalia’s Shebab rebels in their five-year insurgency.

Witnesses described the carnage as the worst they had seen in Mogadishu since Somalia plunged into chaos two decades ago and said the devastation resembled scenes from World War II.

The suicide bomber rammed an explosives-laden vehicle into the compound housing four ministries at a strategic crossroads, two months after the Al Qaeda-linked rebels dismantled all their positions in the capital.

Somali President Sharif Sheikh Ahmed condemned the attack which he said claimed “more than 70 people and (left) 150 injured; most of them were young students.”

“I am extremely shocked and saddened by this cruel and inhumane act of violence against the most vulnerable in our society,” he said in a statement.

The United States, a key Somali government supporter, also condemned the Shebab’s “complete disregard for human life,” State Department spokeswoman Victoria Nuland said.

Somali police spokesman Abdullahi Hassan Barise said the attacker was a Kenyan national named Ashad Abdi Said.

“We have the passport…. He was born in Wajir in northeastern Kenya,” he told AFP.

United Nations chief Ban Ki-moon also expressed shock at the deadly bombing.

“It is incomprehensible that innocents are being senselessly targeted,” Ban was quoted as saying by spokesman Martin Nesirky.

“The secretary general is appalled by the vicious suicide bomb attack targeting government offices and ministries in Mogadishu today.”

The International Committee for the Red Cross said around 90 people had been hospitalised at Mogadishu’s Medina hospital.

Most of the casualties were reported to be civilians, with local residents saying the bomb went off as students were queueing for scholarships offered by Turkey.

“The scene looks like something from World War II. This was total devastation,” said Abdullahi Aptidon, a resident at K4.

“It was a powerful explosion and at first I thought it was a landmine, but the magnitude of the explosion made me imagine something different. This is the worst tragedy since civil war began in 1991.”

According to witnesses, the bomber managed to sneak deep into Mogadishu under the cover of transporting displaced civilians from a nearby camp.

A Shebab official who did want to be named said one of their fighters carried out the attack.

“One of our Mujahidin made the sacrifice to kill TFG officials, the African Union troops and other informers who were in the compound,” he said.

Tuesday’s attack was the deadliest by the Shebab since multiple bombings in Kampala killed at least 76 people in July 2010.

It was also their bloodiest in Somalia since the group formed around five years ago, largely in response to Ethiopia’s occupation.

In a surprise move, the Shebab abandoned their positions in Mogadishu in early August, after years of attempting and failing to break the AU’s defences and take over the capital.

They had vowed however that it was a tactical move and that their struggle against the Western-backed Somali government would continue.

They pulled back to areas they already controlled in the south and west and observers had warned that the Shebab could be reverting to hit-and-run guerrilla tactics.

“Although the extremists have left the capital, it is very difficult to prevent these types of terrorist attacks which we have consistently warned are likely to be on the increase,” said Augustine Mahiga, the UN representative for Somalia, also condemning the attack.

AU and pro-government forces had re-asserted their authority over most of the capital and the Shebab’s withdrawal had led to a relative lull in violence.

The Shebab have rekindled their insurgency on several fronts almost simultaneously, with clashes also reported in western and southern regions.

They launched an attack late Monday in the city of Dhusamareb, which lies in western Somalia near the border with Ethiopia and is the main stronghold of Ahlu Sunna wal Jamaa, a Sufi militia allied to the government.

The UN refuge agency also reported violence in Dhobley, a town on Somalia’s southern border with Kenya and said the clashes were “further exacerbating the already severe humanitarian situation.”

“We have received initial, unconfirmed reports of deaths and scores of injured people,” said Adrian Edwards, spokesman for the UN High Commissioner for Refugees.

Dhobley is under the control of forces from the self-declared state of Azania, an anti-Shebab militia reportedly backed by Kenya to create a buffer zone along the troubled frontier.

The UN Security Council last week urged the AU to increase its 9,000 troops propping up the Somali government.

The Horn of African country has lacked a central authority since plunging into a deadly civil war with the 1991 ouster of president Mohamed Siad Barre.