The federal government has scaled up its military response to the Boko Haram insurgency and will secure the northeast, acting president's spokesman said on Sunday, adding that the search for oil workers abducted by suspected members of the jihadist group will go on.

Members of an oil prospecting team were kidnapped in the northeast's restive Lake Chad Basin region on Tuesday, prompting a rescue bid that left at least 37 dead including members of the team, rescuers from the military and vigilantes, officials say.

Three kidnapped members of the oil team later appeared in a video on Saturday.

The insurgency has killed 20,000 people and forced some 2.7 million to flee their homes in the last eight years, and the frequency of attacks has increased in the last few months. At least 113 people have been killed by insurgents since June 1.

In a statement on Sunday, office of Acting President Yemi Osinbajo said he had ordered the military to "scale up their efforts and activities" in Borno, the state worst hit by the insurgency, to "maintain a strong, effective control of the situation and secure lives and property".

"The federal government of Nigeria is not only on top of the situation, but will define the end of these atrocities by both winning the war and winning the peace in the northeast," said the emailed statement issued by Osinbajo's spokesman.

President Muhammadu Buhari left Nigeria on May 7 to take medical leave in Britain for an unspecified ailment. He handed power to his deputy, Osinbajo, seeking to allay concerns of a void at the helm of Africa's most populous nation.

The government and military have repeatedly said Boko Haram - which also carries out cross-border attacks in neighbouring Cameroon and Niger - was on the verge of defeat.

Buhari said in December that Boko Haram's base in the northeast's vast Sambisa forest had been captured.

The statement issued on Sunday said Osinbajo had ordered the "continuation of search and rescue missions to locate and ensure the freedom of all remaining abducted persons" following the kidnapping of oil workers.

The state oil company has for more than a year surveyed what it says may be vast oil reserves in the Lake Chad Basin as part of a bid to reduce the OPEC member's reliance on the southern Niger Delta energy hub, which last year was hit by militant attacks on oil facilities.

Reuters