He was an outspoken critic of the previous military dictator, Sani Abacha, serving time in prison for his beliefs.

In a country where individual regions are making increasing demands for lucrative oil revenues, Mr Ige, 71, had become involved in a struggle for power between two different factions in the south-western Osun state, where he made his political reputation.

But as well as regional, there are also religious tensions.

Curfews

Mr Ige was critical of the decision by some of the country's northern states to introduce Islamic Sharia law a year ago.

Thousands of people have since died in religious fighting between Christians and Muslims.

Thousands have died in religious violence

Soldiers are now enforcing curfews in five northern cities.

And while the government is struggling to contain religious tension, there is also ethnic bloodletting.

Troops gunned down hundreds of unarmed people in the eastern Benue state two months ago after ethnic militants killed 19 soldiers.

In a country with such a complicated political landscape, finding out why Mr Ige died may prove difficult.