Since independence from Britain in 1960, Nigeria has known only one reasonably successful election, in 1979, when Shehu Shagari, a little-known northern politician, defeated the veteran southerner Obafemi Awolowo.

ECONOMIST: Nigeria��s long road back to democracy

The African contingent is expected to be bolstered to 7, 900, including 2, 200 troops promised by Chad, AP news agency quotes a Nigerian military official, Col Shehu Usman Abdulkadir, as saying.

BBC: Mali crisis: French-led troops 'surround Timbuktu'

In July and August 2012 suicide bombers tried but failed to kill the shehu - or traditional ruler - of the Borno emirate in north-east Nigeria as well as the emir of Fika in Yobe state.

BBC: Nigeria: Kano reels after emir attack

"This violence is also about the poverty, the hunger, the disappointments in the society as much as it is with the refusal to accept the result of this election, " the CRC's Shehu Sani told the BBC.

BBC: African viewpoint: 'Enough is enough'

Ibori was not only a state governor when he committed the alleged crimes, he was also a powerful member of the ruling People's Democratic Party (PDP) and a financier of the presidential campaign of President Shehu Yar'Adua, now late.

BBC: African viewpoint: Scramble for Nigeria's $15m 'bribe'