(Recasts with rescue of oil survey team)

BAUCHI, Nigeria, July 26 (Reuters) - Nigeria's military has rescued all members of an oil survey team kidnapped by suspected Boko Haram militants, it said in a statement on Wednesday, after they were taken in the country's conflict-ridden northeast.

Earlier on Wednesday, the Nigerian National Petroleum Corporation (NNPC) said suspected members of the Islamist insurgency had kidnapped 10 members of a university research team the firm had contracted to prospect for oil in Nigeria's northeast.

The corpses of nine soldiers and a civilian were also recovered during the rescue, the military said. The NNPC did not immediately respond to calls for comment.

The state oil company 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 for eight years by an Islamist insurgency, which has killed at least 20,000 people and forced some 2.7 million to flee their homes.

Nigeria relies on oil for two-thirds of its revenue. The NNPC is trying to reduce its reliance on crude from the southern Niger Delta where militant attacks cut production by more than a third in 2016, deepening the recession in Africa's biggest economy.

NNPC spokesman Ndu Ughamadu said earlier on Wednesday that contractors working as consultants had been kidnapped near Jibi village in Borno state on Tuesday afternoon. The village is in Magumeri local government area, about 50 km (30 miles) from the state capital, Maiduguri.

"About 10 members of the University of Maiduguri geology and surveying department were abducted by suspected Boko Haram members," Ughamadu said. The group included academic staff, drivers and other contractors, he said.

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

Boko Haram, which attained international notoriety after kidnapping 270 girls from their school in the town of Chibok in 2014, is trying to create an Islamic state in the Lake Chad Basin area.

The conflict has not deterred NNPC's search for oil in the region.

"We are working with the security agencies for an early return to the Chad Basin," aiming for drilling to start in the fourth quarter of the year, NNPC chief Maikanti Baru said at the beginning of July.

In May, the NNPC said it would resume oil exploration in the northeast "on the heels of (the) improved security situation".

Nigeria's government and military have repeatedly said Boko Haram is on the verge of defeat. In December, President Muhammadu Buhari said the group's last stronghold, an enclave in the Sambisa forest, had fallen.

But insurgents have launched attacks with renewed zeal in the last few months.

At least 62 people have been killed in Maiduguri and its environs since early June. Seventeen people were killed in the city in one week this month. (Reporting by Ardo Abdullahi in Bauchi and Alexis Akwagyiram in Lagos, Lanre Ola and Ahmed Kingimi in Maiduguri; Writing by Alexis Akwagyiram and Paul Carsten; Editing by Louise Ireland and Richard Balmforth)

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