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