Boko Haram militants have killed at least 21 people in attacks near the northern Nigerian village of Chibok, news agencies reported Friday, as the radical Islamist group steps up its violent campaign ahead of national elections.
The group's nearly six-year insurgency has ravaged wide swaths of northern Nigeria, and the inability of the Nigerian security forces to quell the violence has turned into a major election issue.
The violence prompted election officials to postpone the vote from earlier this month until March 28.
News agencies said the militants were fleeing a government offensive when they conducted the raids on at least two villages.
Chibok was thrust into the public consciousness last April, when Boko Haram kidnapped more than 200 schoolgirls there. The abduction prompted a viral Internet campaign under the hashtag #BringBackOurGirls.
Nigeria's military said Thursday that airstrikes hit Boko Haram bases in the northeast and killed a "large number" of militants. Air force jets targeted training camps and weapons dumps in the Sambisa Forest and the town of Gwoza, two Boko Haram strongholds, a military statement said.
The claims could not be immediately confirmed.
Sambisa is a vast forest that stretches into parts of five Nigerian states and has been a hideout for the Islamic extremist group for years.
Nigerian security forces have claimed successes against Boko Haram, most recently on Wednesday when military forces said they had killed more than 300 militants and retaken 11 towns.
The statements, however, are hard to verify due to fighting and the disruption of mobile phone service in much of the northeast.
Fighting has also intensified in the past month, after Niger, Chad and Cameroon all began deployed larger forces against the militants.
Earlier this week, Boko Haram's leader Abubakar Shekau threatened to disrupt the March 28 election, the latest in a series of threats that have warned Nigerians not to vote.
Witnesses said Boko Haram fighters burned down much of a town in Borno state (Askira Uba) on Sunday and Monday. On Tuesday, bombs went off at three locations around Nigeria, causing dozens of casualties.
The group has killed thousands in the past five years in attacks on schools, towns, markets, churches, mosques and government targets. Last year, the militants seized numerous towns in the northeast to create what Shekau called a caliphate.