Troops and riot police has been despatched to the Nigerian city of Jos after fights between gangs of Muslim and Christian youths led to a reported 12 deaths. “Houses, mosques and churches were set alight and a dusk-to-dawn curfew is now in force. The city has a history of ethnic and religious tension - at least 200 people were killed in 2008 and 1,000 in 2001. Dan Manjang, special adviser on media to the Plateau State governor, said it was not yet known what sparked the unrest on Sunday. He told the BBC's Network Africa programme there were reports it may have started after a football match. Reuters news agency quotes residents saying the violence started after an argument over the rebuilding of homes destroyed in the 2008 clashes. Correspondents say such clashes in Nigeria are often blamed on sectarianism, however poverty and access to resources such as land often lies at the root of the violence.”