Angry Somalia protests after arrest of former Al-Shabab chief

A third day of protests began on Saturday in Somalia over the arrest of the former number two of the Al-Shabab extremist group how had been a leading candidate for a regional presidency.

Officials said at least eight people have been killed so far as angry supporters take to the streets.

In a joint statement, more than a dozen countries - including the US - the African Union mission, and the UN expressed concern and urged all parties to "to respect the integrity of the electoral process" and engage in dialogue following Mukhtar Robow's arrest on Thursday.

Robow's arrest is viewed as a high-profile test of Somalia's treatment of defectors from Al-Shabab - an al-Qaeda linked group considered to be Africa's most dangerous militant outfit.

Somalia's government had welcomed his defection last year, however, not his candidacy to lead South West State, which took some officials by surprise.

Robow was arrested on Thursday by Ethiopian troops accompanied by Somali police, witnesses told The Associated Press. He was flown to the capital, Mogadishu, a Somali intelligence official said. 

Ethiopia's military, which contributes troops to the AU mission, has not commented. Robow's arrest could re-ignite old tensions between Somalia and neighbouring Ethiopia despite recent diplomatic breakthroughs in the Horn of Africa sparked by Ethiopia's reformist new prime minister.

The African Union, meanwhile, denied playing any role in the former jihadi's arrest, following accusations from Somali lawmakers that the AU mission had been involved.

Somalia's security ministry confirmed Robow's arrest, citing the federal government's earlier ban on his candidacy, which said he had not completed the defection process. The ministry also alleged that Robow had failed to renounce extremist ideology, and accused him of mobilising armed forces to threaten the security of Baidoa.

Somali officials have announced that the election for the Southwest presidency will go ahead on Wednesday, even after Robow was arrested. His local supporters in Baidoa have loudly protested.