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Africa editor, BBC World Service
The Islamist group al-Shabab has seized a military base in southern Somalia, which was until recently occupied by Kenyan troops.
Kenyan forces serving with the African Union force in Somalia have also withdrawn from another base in the area, near the Kenyan border.
Somali forces have also been leaving military bases in southern Somalia's Lower Shabelle region, saying they have not been receiving pay or rations.
The Somali prime minister, Hassan Khayre, said soldiers were being paid, but some were not on the payroll.
Al-Shabab continues to occupy large parts of southern and central Somalia, despite an intensification of US airstrikes.
Reporters in the Somali capital, Mogadishu, say a car bomb has exploded at a checkpoint by the national theatre in the city centre.
Some of them have tweeted photos of smoke rising over the city:
A pro-al-Shabab news website reports that the Islamist militant group says it is behind the bombing.
It is not clear if there are any casualties, but ambulances are at the scene, the news website Mogadishu-based Goobjoog reports.
Al-Shabab, which is linked to al-Qaeda, was forced out of Mogadishu in 2011 but continues to mount regular attacks in the city.
- Read: Who are al-Shabab?
Africa editor, BBC World Service
Kenya and Somalia have restored diplomatic relations following a row over the ownership of offshore oil fields.
The Ethiopian Prime Minister Abiy Ahmed helped mediate between the presidents of Somalia and Kenya who held face-to-face talks in Nairobi.
Last month, Somalia's ambassador to Kenya was expelled following reports that Somalia was auctioning off oilfields in a contested area.
Somalia denied it was selling the blocks.
Somalia has taken Kenya to the International Court of Justice over the issue, which has yet to be resolved.
Mr Abiy tweeted pictures of the meeting.
Women have been leading protests against rape in Somalia's Puntland region after a spate of attacks.
BBC Somali, Nairobi
The Burundian contingent of the African Union force in Somalia has pulled out of its base in the capital, Mogadishu.
This is in line with the AU decision to draw down operation in the country, which is affected by an insurgency waged by militant Islamist group al-Shabab.
AU troops have been camping at the base, known as Jalle Siyad military training academy, for the last decade.
It had been the main training facility for Somali army cadets since 1975.
"The facility will be used for its training purposes," Somalia's Deputy Prime Minister Mahdi Mohamed Guled said.
BBC Africa, Mogadishu
At least six aid workers have been abducted by gunmen in Somalia's south-western Gedo region, a local official has said.
The aid workers - all Somalis - were travelling to Bura village when their vehicle was ambushed by the gunmen on Wednesday, district commissioner Iman Adow said.
Some of the aid workers managed to escape, but six were taken captive, he added.
The motive for the abductions is unclear. Some locals blame militant Islamist group al-Shabab for the kidnappings, but the group has not yet commented.
The aid workers are involved in efforts to curb malnutrition among women, children and the elderly, and were going to the village to assess the situation there when they were seized.