FACTBOX-The Africa Union peacekeeping force in Somalia

May 26 (Reuters) - Somali government forces and troops from the African Union Mission in Somalia (AMISOM) launched a new military push on May 12 and have seized several strategic positions from al Qaeda-affiliated al Shabaab insurgents.
Somalia has been bogged down in violence and awash with weapons since the overthrow of a dictator in 1991, with warlords and now Islamist militants stepping into the power vacuum, and allowing piracy to flourish off the country's shores.
While al Shabaab appears to be on the back foot in Somalia, AMISOM has also warned a bitter power struggle among the country's political leaders will risk unravelling the military gains. Here are some details on AMISOM:

BACKGROUND:
-- The African Union Mission in Somalia (AMISOM) is an active, regional peacekeeping mission operated by the African Union with the approval of the United Nations. It was created by the African Union's Peace and Security Council in January 2007 with an initial six month mandate.
-- In January 2011 the AU extended the mandate of the peacekeeping force for another year, defying demands from rebels to withdraw. In May, AMISOM relocated its civilian international staff and police officers to Mogadishu, from the Kenyan capital, Nairobi.

NUMBERS:
-- In December 2010, the U.N. Security Council approved an extra 4,000 peacekeepers for Somalia to bolster the 8,000-strong force in Mogadishu.
-- Uganda and Burundi said in March they would commit an extra 2,000 troops each to the African Union mission in Somalia, bolstering the fight against insurgents.
-- Burundi already deployed 1,000 of the 4,000 extra troops in mid-March.

ATTACKS AND CASUALTIES:
-- AMISOM has been fighting to keep Islamist insurgent groups from overthrowing the government.
-- Its forces control more than 60 percent of the capital. Horn of Africa experts have said they were all that prevent the insurgents from toppling an administration plagued by internal rifts and corruption.
-- AMISOM troops are closing in on Bakara market, the nerve-centre of rebel operations in the capital. The bazaar is seen as key to regaining control of Mogadishu. -- The May offensive is the second in 2011 to regain control of insurgent-held neighbourhoods and weaken the rebels fighting to overthrow the Western-backed government, before ultimately flushing them out of the capital.
-- It is unclear how many peacekeepers have been killed since the outset of their operations. For a long time AMISOM played down casualty number. At least three AU peacekeepers were killed earlier this month during a battle in Mogadishu.
Sources: Reuters/ allAfrica.com (For full Reuters Africa coverage and to have your say on the top issues, visit: africa.reuters.com/ ) (Writing by David Cutler; Editing by Richard Lough)