Three female suicide bombers have carried out an attack that has killed at least 27 people in north-eastern Nigeria, officials say.

Dozens were injured when the women blew themselves up outside a refugee camp near Maiduguri in Borno state - a stronghold of the Islamist militant group Boko Haram.

Zimbabwean First Lady Grace Mugabe has so far failed to appear in a South African court over an assault case despite officials saying she would do.

South African police said in the late afternoon they did not know where Mrs Mugabe was.

Kenya's opposition presidential candidate, Raila Odinga, has said the electoral commission's IT system has been hacked to manipulate the election results.

He has rejected early results from Tuesday's vote, indicating a strong lead for President Uhuru Kenyatta.

Amnesty International thinks that the recent events in Kenya, including the murder of a top electoral commission official, are creating a cloud of fear that must be properly addressed ahead of next week’s election.

In a statement issued on Tuesday, Muthoni Wanyeki, Amnesty International’s Regional Director for East Africa, the Horn and the Great Lakes: “This brutal murder has sent a chill down the spine of many Kenyans and raised the spectre of violence.”

Angola says it will allow four experts from the European Union (EU) to monitor its election later this month, the AFP news agency reports.

"The EU will only send a small mission... We cannot really speak of observers, only experts. A real mission of observers is 200 people," a European diplomatic source told the AFP.

Somalia officials say a key al-Shabab commander has been killed in an American airstrike.

A statement from the US Africa Command did not name the dead man, but said one fighter had been killed near Tortorow in southern Somalia.