Nigeria's president on Wednesday gave experts six weeks to explain what led to the spate of election-related violence which marred a series of polls that had burnished the democratic image of the oil-rich West African nation.
A wave of riots that spread across northern states after the April 16 presidential election left at least 500 dead and more than 40,000 people displaced in northern Nigeria.
President Goodluck Jonathan told journalists Wednesday that a committee would determine how many people died, what led to the violence and where rioters got their weapons.
While international observers applauded Nigeria's legislative and presidential elections held in April, the violence that erupted in the aftermath threatened the stability of the oil-producing West African nation.
"This unfortunate development was no doubt meant to mar what ought to have been a celebration of the progressive march of our democratic experience," said Jonathan, who won a four-year term in an April 26 vote.
Many in Nigeria's predominantly Muslim north were angered, however, that Jonathan _ a Christian from the south _ had won. The riots started just as it became clear that his main opponent, Muhammadu Buhari _ a Muslim from the north _ was losing.
The last elected president, Umar Musa Yar'Adua, was a Muslim northerner but he died before his term ended. He had been expected to rule for another term, but his death catapulted his vice president to power, leaving the presidency of Africa's most populous nation in the hands of a southerner before that region's turn.
An unwritten agreement in the ruling party calls for its presidential candidates to rotate between the country's Christian south and Muslim north.
As security forces struggled to quell the violence, Jonathan told CNN that the riots had not been spontaneous, adding that authorities would investigate their origin.
But a lawyer of Buhari's party, the Congress for Progressive Change, has accused Jonathan's government of pushing people to revolt.
"Our national history has however taught us that the determination to win elections by incumbents by any means has always given birth to spontaneous reactions in the form of breakdown of law and order," said Abubakar Malami.