KANO, Nigeria - Post-election riots in northern Nigeria left many dead, thousands displaced and hundreds wounded on Tuesday amid claims that bodies had been thrown into wells in areas hit by unrest.

Nigerian President Goodluck Jonathan called on political and religious leaders to condemn the violence over his election victory, adding that most of the rioters appeared to be "unemployed young people".

He pledged that the government would work to change their situation "so that they will no longer be tools for people to use".

Fearing reprisals, authorities have not given a death toll for the rioting that began sporadically during the weekend over allegations of vote rigging and quickly spread to some 14 states on Monday. Officials have however spoken of many killed.

An estimated 25,000 have been displaced and some 375 wounded, according to the Red Cross. Police said dozens of people had been arrested.

"Things are relatively calm right now, but violent protests went on last night, especially in Kaduna, Katsina and Zamfara (states)," said Umar Abdul Mairiga, the Nigeria Red Cross disaster management coordinator.

"What may come out of there is not very palatable because many people were killed, especially in southern Kaduna. The displaced people are getting hostile because nothing is coming up in terms of relief."

Jonathan, the first president from the southern oil-producing Niger Delta region, was declared late on Monday winner of a landmark vote that exposed regional tensions and led to the deadly rioting.

He took 57 percent of the ballots in Saturday's election in Africa's most populous nation, easily beating his northern rival, ex-military ruler Muhammadu Buhari, who had 31 percent.

Nigeria is roughly divided in half between a mainly Muslim north and predominately Christian south.

Buhari, whose party has rejected the results and filed a challenge to them, has not spoken publicly but condemned the rioting in brief comments to the BBC's Hausa-language service.

Police were providing few details on the situation. While the initial rioting began over allegations that Jonathan's party had sought to rig the vote, the situation appeared to be more complex in some instances.

Agence France-Presse