Nigeria, Africa's most populous country, is set to begin three consecutive weeks of elections.

Some 73 million people have registered to vote in the parliamentary, presidential and gubernatorial polls on the next three Saturdays.

Security is high, with borders closed and only election officials, security forces and emergency personnel allowed to drive on roads during voting.

Earlier, politicians were urged to put a stop to campaign violence.

Amnesty International said at least 20 people had been killed in related attacks and clashes over the last two weeks.

A bomb was thrown into a police station in the city of Bauchi on Friday in an apparent attempt to cause panic. No casualties were reported.

Police in the Niger Delta also said they had arrested two men driving a minibus filled with assault rifles, ammunition and a rocket launcher.

Sanctions threat
This is the third time nationwide elections are being held in Nigeria since military rule ended in 1999.

The previous ones - in 2003 and 2007 - were marred by allegations of widespread ballot stuffing, voter intimidation and violence.

Security forces were also accused of siding with the People's Democratic Party (PDP), which has dominated politics since the return to civilian rule.Security forces were also accused of siding with the People's Democratic Party (PDP), which has dominated politics since the return to civilian rule.

The chairman of the Independent National Electoral Commission (INEC), Attahiru Jega, has promised that this time the polls will be free and fair.

"Twelve years ago, our dear country, Nigeria, returned to democratic rule and we began a journey that many expected by now would have produced a stable democratic system in which peaceful, free, fair and credible elections are routine and taken for granted," he told reporters.
Read more: Bimanie