Elections for the governors of two states in Nigeria's predominantly Muslim north have been postponed because of violence, officials have announced.
The region has been hit by days of deadly violence since Goodluck Jonathan, a Christian from the south, won Saturday's presidential election. At least 200 people have been killed and several thousand injured in riots in northern areas.
The electoral commission said that the poll on Tuesday would not go ahead in Bauchi and Kaduna states, because of security concerns. The announcement came just hours after Jonathan vowed in a televised address to the nation that the elections for state governors would go ahead, as order was being restored to the nation.
"My fellow countrymen and women, enough is enough," Jonathan said in a televised address to the nation, on Thursday. "Democracy is about the rule of law."
"These disturbances are more than mere political protests. Clearly they aim to frustrate the remaining elections. This is not acceptable."
"These acts of mayhem are sad reminders of the events which plunged our country into 30 months of an unfortunate civil war," he said, referring to killings that led to a conflict in which one million people were killed in the 1960s.
Jonathan said security services would deal "decisively" with any further unrest.
"I assure you all that calm is being restored in troubled parts of the country and that the elections scheduled for next Tuesday will go on as planned."
Displaced by violence
Rioting erupted in major northern cities after incumbent Jonathan, who heads the People's Democratic Party (PDP), was declared winner of the presidential poll with 57 per cent of the ballots, easily beating his rival, Muhammadu Buhari, with 31 per cent.
Al Jazeera's Yvonne Ndege reports on the deadly violence following presidential elections in Nigeria
An estimated 40,000 people have been displaced in the violence in the country's mostly-Muslim north.
A Nigerian civil rights group based in the northern state of Kaduna put the number of deaths in the unrest at more than 200 across the north, after rioting broke out on Sunday.
"In the whole region, from reports reaching Civil Rights Congress, the death toll is over 200," Shehu Sani, the head of the organisation, told the AFP news agency.
There were reports of fresh clashes in an area of Kaduna overnight, with a community leader telling local radio "the killing was unbelievable and the destruction is colossal".
Analysts have said that the upcoming governorship elections could hold the most risk of violence. Governors have significant power in Nigeria, granted huge budgets due in part to oil revenue.
Jonathan's election rival Buhari, a northerner, has alleged irregularities in the presidential vote.
He said people just "reacted to the results" and said he did not know what triggered the violence.
"It was so spontaneous that I didn't know about it. I did not ask them to start it, but I asked them to stop, especially the burning of churches and other religious places."
Buhari, a former military ruler, also denied instigating the deadly violence in the north but blamed it on what he called a rigged election.
Observers have largely said that Saturday's presidential election appeared to be fair, and was a significant improvement over last elections 2007.
Al Jazeera's Yvonne Ndege, reporting from Kaduna - which has been hit by some of the worst violence, said the violence seems to have been based along religious lines.
"There are Muslims here, there are Christians here. There are those out there who are prepared to use religion to target opponents," she said.
"What is underneath all of this is the feeling and the sense that the president should not have run in the 2011 race because of an informal agreement that says the North is supposed to produce the next president.
"It's not just the presidential race - 10 days ago we had parliamentary elections and in a week's time we've got governorship elections. We've seen all candidates exploit religious difference, ethnic difference, tribalism, youth party organisation, rigging to win votes.
"Even now in Kaduna state we are getting reports - we're inundated in fact with eyewitness accounts - of people barricaded in their homes for fear of going out and being caught up in the mayhem."
Nigeria, a nation of 150 million people, is roughly divided between the Christian-dominated south and the Muslim north. A dozen states across Nigeria's north have Islamic Shariah law in place, though the area remains under the control of secular state governments.