MAIDUGURI, Nigeria, Sept 28 (Reuters) - Gunmen from Islamist group Boko Haram killed 27 villagers in two attacks in Nigeria's restive northeast this week, a government official said, as violence continued to flare in the face of an army crackdown on the militants.
Boko Haram wants to create an Islamic state in northern Nigeria and has become the biggest security threat in Africa's second largest economy and top oil exporter.
Six people were killed in an attack on Wednesday night in Gamboru, a remote town close to the Cameroon border in Borno state, local government chairman Alhaji Modu Gana Sheriff told reporters.
Sheriff said gunmen returned on Thursday night and killed 21 more civilians. A Borno military source said he thought the attacks were coordinated and confirmed the death toll.
Authorities have disconnected phone lines in Borno to try to disrupt Boko Haram's operations, which means it often takes days for news of attacks to reach state capital Maiduguri.
Violence has intensified over the past two months, as the Islamists fight back against a military operation that President Goodluck Jonathan ordered in May to try to crush their four-year-old rebellion.
There was an initial lull in the violence when the military operation started in May and Islamists fled their bases in cities, forests and mountains across the northeast.
But then the militants started revenge attacks, first on schools, seen as focuses of the Western culture they despise, then on the security forces and the civilians they believed were helping the army.
Several hundred people have died in attacks over the past few weeks. Some observers say the army offensive has only succeeded in pushing attacks away from well-guarded large towns and cities into vulnerable rural areas.
Thousands have been killed since Boko Haram launched its uprising against the state in 2009, turning itself from a clerical movement opposed to Western culture into an armed militia with growing links to al Qaeda's West African wing. (Reporting by Lanre Ola; Writing by Joe Brock; Editing by Andrew Heavens)