(adds details, background)
By Abdiaziz Hassan
DJIBOUTI, Feb 13 (Reuters) - Somalia’s president has chosen Omar Abdirashid Ali Sharmarke, the U.S.-based son of a slain former leader, to be prime minister in a unity government it is hoped will end civil conflict, official sources said.
President Sheikh Sharif Ahmed’s nomination was to be formally announced later on Friday in Djibouti, where Somali politicians are meeting, the senior government sources said.
"The president has signed the nomination paper and met with the prime minister designate," an aide to Ahmed said.
Ratification by parliament is expected to be a formality given new president Ahmed’s wide backing in the legislature.
Sharmarke, who has held various United Nations posts and was educated in the United States, is the son of Abdirashid Ali Sharmarke, a popular elected president who was assassinated in 1969 during a military coup.
"Omar is expected to be like his father, who was very loved by the Somali people," another official said.
Sharmarke, who is in his late 40s, is a member of the Darod ethnic group, whereas Ahmed is Hawiye.
Somalia’s government is meant to share key positions among the major communities.
By choosing Sharmarke, Ahmed will hope to win support from the Somali diaspora and also bolster international support for his fledgling government, which has been set up under a U.N.-brokered peace process in Djibouti.
The major challenge for both president and prime minister will be to face the threat of armed Islamist insurgents in Somalia led by the al Shabaab group, which is on Washington’s list of terrorist organisations.
Al Shabaab says Ahmed’s government is an illegitimate "puppet" administration put together by foreign powers. Although Ahmed is a moderate Islamist who used to lead a sharia courts movement in Somalia, al Shabaab denounces him as anti-Islamic.
Somalia has been without effective central government since 1991.
(Writing by Andrew Cawthorne; editing by Michael Roddy)