Pope Benedict XVI called Wednesday on those responsible for violence in Nigeria to \"stop spilling the blood of innocent people\", and urged all parties involved not to seek revenge. \"I appeal to those responsible for the violence to immediately stop spilling the blood of innocent people,\" he said, following attacks on churches in northern Nigeria and reprisal violence that saw Christians target Muslims. \"I hope all parts of society will collaborate in not taking the road of reprisals,\" Benedict said during a weekly general audience. Sunday\'s attacks against churches, claimed by Islamist group Boko Haram, and a wave of revenge attacks that followed, were the latest in a series. In front of 8,000 faithful gathered at the Vatican, the pope appealed on \"all Nigerian citizens to cooperate in the construction of a peaceful and reconciled society in which the right to freely express faith is guaranteed.\" Nigeria\'s main Christian body on Tuesday said the attacks by Boko Haram suggested a \"systematic religious cleansing\". There have been renewed concerns over whether the violence could lead to a wider sectarian conflict in a country roughly divided between a mainly Muslim north and mostly Christian south. Boko Haram\'s demands have varied, prompting speculation that the group is composed of disparate cells, including a hardcore Islamist wing. The extremists have previously said they intended to create an Islamic state across the mainly Muslim north of Nigeria, Africa\'s most populous nation of 160 million and the continent\'s largest oil producer.