Suspected Boko Haram insurgents have kidnapped 10 members of a geological research team from the University of Maiduguri in northeast Nigeria, the state oil company, which contracted the work, said on Wednesday.

The Nigerian National Petroleum Company (NNPC) has been surveying for more than a year for what it says could be vast oil reserves in the Lake Chad Basin, a region wracked by Boko Haram’s eight-year insurgency, which has killed at least 20,000 people and forced millions to flee their homes.

OPEC member Nigeria relies on crude oil for two-thirds of government revenue. Attacks on energy facilities in its southern Niger Delta oil heartland last year cut production by more than a third, deepening the recession in Africa’s biggest economy.

NNPC spokesman Ndu Ughamadu said the contractors were kidnapped near Jibi village in Borno state on Tuesday afternoon.

“About 10 members of the University of Maiduguri geology and surveying department were abducted by suspected Boko Haram members,” Ughamadu said, noting that the group included academic staff, drivers and other workers.

The University of Maiduguri said some of its lecturers, who were accompanied by security staff, had not returned on Tuesday from an oil prospecting trip. Its spokesman said the university was waiting for a report from security agencies.