Kenya has appealed to donors after its plan to shut down the world's largest refugee camp and send Somalis back home ran into funding problems, reports said Wednesday.

Kenya threatened to close the Dadaab camps and send home more than 360,000 Somali refugees within 90 days amid security fears in the wake of this month's Garissa University massacre by Somalia's Shebab insurgents in which 148 people died.

The United States blacklisted two top leaders of Somalia's Shebab on Tuesday, a day after the Islamist group killed seven people, including four U.N. workers, in a huge bus bombing.

Ahmed Diriye, who took over as the militant group's leader in September 2014, and intelligence chief Mahad Karate, were both designated as terrorists by the State Department.

Three people were killed and six wounded in a car bomb blast outside a popular restaurant in the center of the Somali capital Mogadishu on Tuesday, police said.

The attack is the latest in a string of bombings in the war-torn Horn of Africa nation, where Al-Qaida-affiliated Shebab Islamists are fighting to topple the government.

The U.N. children's agency mourned Tuesday four staff members killed in what U.N. chief Ban Ki-moon condemned as a "barbaric attack" in Somalia.

Two of those killed in Monday's bombing in the northeastern town of Garowe came from Kenya, the other two from Afghanistan and Uganda.

The captain of a migrant boat that capsized in the Mediterranean's deadliest disaster in decades was arrested Tuesday on suspicion of causing the deaths of an estimated 800 people.

Prosecutors in the Sicilian city of Catania said they believed Tunisian national Mohammed Ali Malek, 27, was responsible for steering mistakes and the reckless overcrowding which led to the horrifying shipwreck off Libya on Sunday.

Six Somali-American men who planned to travel to Syria to fight with Islamic State jihadists have been arrested and were to appear in court Monday on charges of conspiring to support a terrorist organization.

The case was the latest in a series in recent months concerning Americans who have been accused of or stopped from traveling to the Middle East to join extremist groups.

Somalia's Shebab Islamists killed at least six U.N. workers on Monday when they set off a huge bomb which ripped through a staff bus in the northeastern town of Garowe, police said.

Four of those killed worked for the U.N. children’s agency, Unicef, while four other Unicef staff were in a "serious condition", the agency said in a statement.

Somalia's Shebab militants killed three soldiers from the African Union force fighting them in Somalia on Sunday, the AU said, condemning the latest in a series of attacks by the Islamists.

AU envoy to Somalia Maman Sidikou condemned "the cowardly ambush" on a convoy of troops on Sunday in southern Somalia's Lower Shabelle district, between the small settlements of Lego and Balidogle.

All four gunmen from Somalia's Al-Qaida linked Shebab who carried out the Kenyan university massacre earlier this month were Kenyans themselves, reports said Thursday.

The militants attacked the university in the northeastern town of Garissa on April 2, lining up non-Muslim students for execution and killing 148 people in what President Uhuru Kenyatta described as a "barbaric medieval slaughter".

Kenyan youths have begun construction of a security barrier along the vast and porous border neighboring war-torn Somalia, although critics have dismissed the project as infeasible, reports said Thursday.

The proposed barrier is the latest in a string of measures Kenya has announced to stem attacks by Somalia's Al-Qaida-linked Shebab insurgents in the wake of a university massacre in the northeastern town of Garissa.