(http://news.bbcimg.co.uk/media/images/75329000/jpg/_75329063_nigeriamaidugurigwozamandara4640614.jpg) On 1 June at least 14 people were killed in a bomb attack on a bar in Adamawa that was screening a televised football match. No group claimed responsibility for the blast.
In March, many people were also killed in explosions while watching football in a video hall in Borno's Maiduguri town. On both occasions, Boko Haram was blamed for the blasts.
Boko Haram - which means "Western education is forbidden" in the Hausa language - wants to overthrow the government and create an Islamic state.
The group captured international attention in April after it abducted more than 200 girls in Chibok in Borno state.
The states of Borno, Yobe and Adamawa have been under a state of emergency since May 2013. Thousands have died in the north-east since Boko Haram launched an insurgency in 2009.
Nigeria's military has promised increased security but there are still daily reports of attacks on villages in parts of the north-east.
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A 60-second guide to Boko Haram
Source: BBC.co.uk