At least five members of an oil exploration team kidnapped by suspected Boko Haram militants in northeast Nigeria have been killed, a university spokesman said on Thursday.

The military said a day earlier that it had recovered the bodies of nine soldiers and a civilian during its rescue of all staff from the Nigerian National Petroleum Corporation (NNPC) who were on the survey team.

The military's statement did not refer to team members from the University of Maiduguri, however, which contributed staff including geologists to the team surveying in the conflict-ridden Lake Chad Basin region.

A spokesman at the university, deputy director of information Ahmed Mohammed, said on Thursday that two university academics and at least one driver were among at least five dead.

Four others staff members from the university are missing, he said.

A military spokesman did not immediately reply to phone calls and text messages requesting comment.

Northeastern Nigeria has been wracked for eight years by an Islamist insurgency that has killed at least 20,000 people and forced some 2.7 million to flee their homes.

The NNPC, which contracted university staff, has for more than a year surveyed what it says may be vast oil reserves in the Lake Chad Basin. It is aiming to reduce its reliance on the southern Niger Delta energy hub, which last year was hit by militant attacks on oil facilities.

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