Nigerian Islamist sect Boko Haram was suspected of carrying out the bombings of three churches in the Christian north of Nigeria.
Boko Haram has been implicated in church bombings as part of its campaign to establish an Islamic state in the oil-rich African nation.
Benedict, during an address from the Vatican, called for an end to the violence in Nigeria.
"I am following with deep concern the news from Nigeria, where terrorist attacks are continuing, especially against Christians," he was quoted by the BBC as saying. "I appeal to those responsible for the violence to immediately stop spilling the blood of innocent people."
Nigerian President Goodluck Jonathan, a Christian, has been criticized for his perceived inability to tackle the crisis, though authorities said it's difficult to identify Boko Haram members because they blend in with society.