Nigeria's National Conference starts in Abuja
A National Conference to discuss Nigeria's future is opening, with the division of oil money and powers expected to be the main issues.
Some 500 delegates are attending, representing Nigeria's many ethnic, linguistic and religious groups.
The National Conference comes 100 years after the mainly Muslim north and largely Christian south were united.
Delegates have been barred from discussing whether the country should be divided.
However, some groups say they will still raise this issue during the three-month conference in the capital Abuja.
Critics, including the main opposition party, have dismissed the conference as a waste of time and money.
The oil is located in southern Nigeria and some delegates from oil-producing areas want local communities to keep more of the revenue it generates.
However, poverty levels are far higher in the north and delegates from non-oil-producing areas are expected to resist such moves.
At present, oil states keep 25% of the oil revenue they earn and hand the rest to the federal government.
Nigeria is one of the world's biggest oil producers but most of its 170 million people live in poverty.
Some Nigerians want more powers to be delegated to the country's 36 states.
BBC Hausa editor Mansur Liman says it appears as though President Goodluck Jonathan wants to use the conference to change the constitution, which would otherwise be very difficult to achieve.
The conference comes ahead of elections next year, in which the governing People's Democratic Party is expected to face its strongest challenge since the end of military rule in 1999.
It also comes amid almost daily attacks by militants, suspected to be from Boko Haram, which wants to govern northern Nigeria according to Islamic law.