The leader of Nigeria's Islamist group Boko Haram has defended recent attacks on Christians, and warned of more to come.

In a video posted on Youtube, he warned that Nigeria's security forces would not be able to defeat the group.

The rise in religious tensions is another headache for President Goodluck Jonathan who's facing a fourth day of nationwide strikes over the rising cost of fuel.

Al Jazeera's Haru Mutasa reports from the capital Abuja.