A police officer at the scene of the latest bombing said four bodies and 48 injured people had been taken away.
Witnesses said the blast went off in the packed market neighbourhood of Kasuwar Arawa.
A Nigerian security source said the bomb went off at 12:15 p.m.
The bomber blew himself up near a line of Sunni pro-government fighters waiting for their salaries.
Kabul criminal investigation police chief says first attacker hit a bus with Afghan National Army officers, killing seven.
The attack took place near the town of Afgoye, some 30 kilometres northwest from the capital Mogadishu.
The bombing was followed by clashes with militants who tried to overtake the town.
Worst bombing since 2001; over 40 injured.
A suicide bomber detonated his explosives-laden vehicle alongside the armored car of Mohammed Masoom Stanikzai.
Six soldiers and a civilian were killed in three separate bombings in Pakistan, including twin blasts in Islamabad.
Iraq has been hit by a year-long surge in bloodshed driven principally by widespread discontent among its Sunni Arab minority.
The bus was carrying 33 South Korean tourists and two Egyptians when the bomber detonated his explosives.
Day after attack on troops, Taliban claim responsibility for another bombing.
The attack comes a day after a Taliban bombing that killed at least 20 troops.
Hashmat Stanekzai, a spokesman for Kabul police, said an operation to clear the building was under way.
Best of Express