A car bomb ripped through a government compound in Mogadishu Tuesday, killing around 50 people in one of Somalia’s deadliest ever suicide attacks, officials and witnesses said.

A car bomb ripped through a government compound in Mogadishu Tuesday, killing around 50 people in one of Somalia's deadliest ever suicide attacks, officials and witnesses said.

The attack was claimed by the Qaida-inspired Shebab insurgents and came as the rebels launched attacks in the country's west and south.

"We fear up to 50 (dead). We understand it is a vehicle bomb," said an official from the Mogadishu-based African Union force who did not want to be named.

A Shebab official who spoke to Agence France Presse on condition of anonymity said one of the insurgent group's fighters had carried out the attack.

"One of our Mujahidin made the sacrifice to kill TFG (Transitional Federal Government) officials, the African Union troops and other informers who were in the compound," said the Shebab official.

Mohamud Abdullahi, a taxi driver, said a car had driven into the compound and exploded. He had spoken of an initial toll of 10 dead and more than 20 wounded.

AU and government troops deployed heavily to the area and cordoned it off.

The explosion is thought to have gone off as students were queuing for scholarships offered by Turkey, which recently stepped up its involvement in Somalia and pledged to re-open an embassy in Mogadishu.

If the death toll is confirmed, Tuesday's attack is the deadliest carried out by the Shebab insurgents since multiple bombings in the Ugandan capital Kampala killed at least 76 people in July 2010.

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 defenses 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.

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 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 Shebab made a surprise offensive late Monday and remained in Dhusamareb for hours before they withdrew," local resident Abdullahi Yasiin said, describing the Shebab's first attack in the area in months.

According to other witnesses, the Shebab withdrew from the city after brief exchanges of fire.

The U.N. refuge agency also reported violence in Dhobley, a town on Somalia's southern border with Kenya.

"The renewed clashes are between opposing armed groups and are further exacerbating the already severe humanitarian situation," said Adrian Edwards, spokesman for the U.N. High Commissioner for Refugees.

"We have received initial, unconfirmed reports of deaths and scores of injured people," he said, without specifying which armed groups were involved in the fighting.

Somalia has been without a central government since the regime of former dictator Mohamed Siad Barre collapsed in 1991 and has been plagued by almost uninterrupted violence ever since.