Nigerian journalists covering their country's World Cup match with Bosnia on Saturday wore t-shirts protesting the Boko Haram Muslim militant group.

Reporters wore t-shirts with the slogan 'World unites against Boko Haram', days after a bomb killed 21 fans watching a World Cup match on a big screen in the northern Nigeria on Tuesday.

A further 10 people died on Saturday in raids by suspected Boko Haram gunmen near villages where Islamists abducted more than 200 girls in April, residents and local leaders said.

"We felt it was important to wear these t-shirts," Steven Alabi Akimjidi, a Nigerian journalist told AFP.

"We would feel comfortable wearing these back home, but not in the region where Boko Haram operate," he added.

The bombing took place as fans were gathered to watch Brazil's goalless draw with Mexico, 24 hours after Nigeria's opening draw with Iran on Monday.

Nigeria face Bosnia later Saturday with a win pushing them to the verge of getting through to the knockout stages in a group where Argentina have already qualified.