Abuja - Nigeria is set for talks on the major issues gripping the nation, from deadly Boko Haram violence to curbing rampant corruption, how to share the spoils of oil wealth and tackle grinding poverty.
A national conference begins in Abuja on Monday, bringing together representatives of hundreds of ethnic, religious and linguistic groups that make up Africa's most populous nation.
But one subject strictly off limits is whether the country should break apart -- a sign of how politically explosive the issue remains as Nigeria marks 100 years since British colonialists merged the north and south.
The talks can touch on "any subject matter except the indivisibility and indissolubility of Nigeria as a nation", said the country's top civil servant, Anyim Pius Anyim.
President Goodluck Jonathan's government has also warned: "The unity of Nigeria is not negotiable."
Ganiyu Adams, who leads a group pushing for a sovereign state for Yoruba people, said the talks may be a last chance to keep the country together.
"There are problems in all the regions. If we don't have the national conference, the country may collapse," he said.
'Pointless and costly'
Amid mounting anger over massive corruption, poor governance, chronic infrastructure problems and a growing wealth divide, some commentators now fear that Nigeria is reaching a tipping point.
For its supporters, such conferences are a chance to open up Nigeria's closeted politics, allowing scrutiny beyond the usual cabal of politicians, military officers and businessmen.
But with talks set to last three months, opponents have condemned the exercise as pointless and costly.
The main opposition All Progressives Congress (APC) has argued the money could be better spent improving access to education and healthcare and alleviating poverty.
"You don't need a national conference to provide infrastructure, you don't need a conference to provide quality education," said Lagos State governor and APC member Babatunde Fashola.
The Joint Action Front, a pro-worker pressure group, called the conference "a wasteful jamboree," and urged all unions participating in the talks to back out.
Analysts argue that such talks have been used in the past merely to make last-minute promises ahead of general elections, with little meaningful substance.
Jonathan is expected to seek re-election as president in polls due in February 2015.
Usman, a doctoral candidate at Britain's Oxford University, called previous editions "crisis-management instruments hurriedly organised to stem imminent crisis or to further a specific political agenda on the eve of a political transition".
Although some constitutional changes have been achieved at past conferences, Zainab Usman wrote on the African Arguments website earlier this year that they had been "reactionary rather than proactive" and ineffective at addressing "existential challenges".
The president has claimed he was initially opposed to the idea of a national conference but changed his mind.
"When there are issues that stoke tension and bring about friction, it makes perfect sense for the interested parties to come together to discuss," Jonathan said in his Independence Day speech last October.
With the country's unity off the table, key topics for debate will likely centre around the effectiveness of the federal government system, control over natural resources and power-sharing.
There has been considerable pressure on Jonathan to rotate power between north and south in recent months.
His power base has been weakened in recent months following the defection of several northern governors and lawmakers over the issue.
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