Authorities in the Somali capital of Mogadishu have said a powerful explosion has killed 11 people.

Most of the dead are said to be Islamist fighters, attempting to overthrow the government.

They say the blast may have been caused when preparations for a car bomb went wrong and the bomb went off prematurely.

Al Qaeda-linked al Shabaab and other Islamist militia have been fighting Somalia's Western-backed government since the start of 2007, launching frequent attacks on its bases in the capital.

‘They are three Pakistanis, two Indians, one Afghani, one Algerian, and two Somalis, (and) a leader who was in charge of praying for suicide bombers before they were dispatched,’ the Somali information ministry said in a statement.

More than 21,000 Somalis have been killed in fighting since the start of the insurgency and 1.5m have been uprooted from their homes with nearly 500,000 sheltering in other countries in the region.