A suicide bomber blew himself up Wednesday at the compound of Somali President Sharif Sheikh Ahmed, killing at least two people, police said.

The bomber detonated an explosive vest at the highly guarded compound, but it was not immediately clear if President Sharif Sheikh Ahmed, who was in Ethiopia on Tuesday, was back in the country.

African Union-backed Somali government troops attacked hardline Shebab insurgent positions at dawn on Friday in the war-torn capital of Mogadishu, officials said.

An artillery barrage first poured down on a northeast district -- which AU forces claim was already largely abandoned by civilians -- before tanks and ground troops moved into the area.

A missile strike killed four al-Qaida allied Shebab rebels in war-torn southern Somalia, officials and witnesses said Friday.

"An Al-Qaida commander was targeted in Lower Shabelle early on Friday morning, a missile struck and destroyed his vehicle, killing him and several colleagues," said a Somali government official.

Truckloads of Ethiopian and Somali troops on Wednesday captured the strategic Somali city of Baidoa from Al-Qaida-allied Shebab insurgents, who vowed to avenge the loss.

"We have taken control of Baidoa without a single shot, it is a great day for the people who are now welcoming us warmly," said Muhidin Ali, a Somali government military commander in Baidoa.

Somalia's al-Qaida-allied Shebab rebels warned Saturday they were stepping up a bombing campaign in the war-torn capital Mogadishu, a day after a car bomb at a police station wounded two.

Shebab spokesman Sheikh Abdulaziz Abu Musab said the extremist Islamist fighters had prepared a string of suicide bombers in their battle to topple the weak Western-backed government and the African Union troops who guard it.

A car bomb exploded inside the compound of a major police building in Somalia's war-torn capital Mogadishu on Friday, wounding at least one police officer, officials said.

"A car full of explosives, which was seized by the security forces this morning, exploded -- a policeman was injured," said Abdulahi Ahmed, a Somali police official. "We are still investigating the incident."

African Union-backed Somali government forces attacked Islamist Shebab rebel posts on the outskirts of the war-torn capital Mogadishu with tanks and artillery Tuesday, officials and witness said.

Burundian troops with the AU Mission in Somalia (AMISOM) launched a pre-dawn attack against holdout positions of the al-Qaida-allied Shebab, to secure a key road leading from anarchic Mogadishu to the rebel-held town of Afgoye.

Britain appointed Thursday its first ambassador to war-torn Somalia for 21 years, Foreign Secretary William Hague said, as he made a landmark visit to the anarchic capital Mogadishu.

"I am delighted to have made the first visit to Mogadishu by a British Foreign Secretary for over 19 years. This is a sign of Britain's commitment to the people and country of Somalia," Hague said in a statement.

A Lebanese-British fighter with the Islamist Shebab militia in Somalia was killed Saturday during a drone attack in the capital Mogadishu, said the movement's spokesman Sheik Ali Mohamoud Rage.

"This afternoon unmanned aircraft bombed and killed our brother Hilal al-Barzawi from Lebanon with British citizenship who fought in Somalia for a long time," he told reporters.

A foreigner has been kidnapped in a semi-autonomous province of central Somalia, a local official said Saturday.

"We have reports that a foreigner has been abducted from Galmudug," security official Ali Abdulrahman said, adding that he had been on the airport road near the town of Galkayo and was believed to be in the employ of the local government.