Somali leader rushed to hospital

President Yusuf has survived several assassination attempts

Somalia's interim President Abdullahi Yusuf has been taken to hospital in the Kenyan capital, the BBC has learnt.

His condition is said to be "serious" but there are no further details. He had a liver transplant in the 1990s.

He is to be flown to London for treatment and has cancelled a meeting on Wednesday with regional leaders.

The news comes as four ministers resigned from the cabinet named by Mr Yusuf's newly appointed Prime Minister Nur Hussein Hassan.

The ministers complained that their Rahanwein clan was under-represented in the government.

Mr Yusuf, 73, had been due to travel to the Ethiopian capital, Addis Ababa for Wednesday's meeting between regional leaders and US Secretary of State Condoleezza Rice.

He was appointed by the transitional parliament in 2004 after years of talks in Kenya.

He is a northerner, from Puntland, and a member of the Darod clan who had been an army commander during Siad Barre's rule and subsequently a guerrilla leader.

President Yusuf controversially enlisted the help of the Ethiopian army to oust the Union of Islamic Courts from the capital, Mogadishu in December 2006.

The past year has seen increasing levels of violence as the Islamists battle the Ethiopian-backed government, rendering Mogadishu too unsafe for the government which has been forced to operate out of Baidoa.

Somalia has not had a functioning national government since 1991.