Goodluck Jonathan made the claim after reviewing a video released last week by a faction of Boko Haram in which they claimed all the hostages were killed, Leadership Newspapers reported Tuesday.
While speculating that some of the hostages may have died from health conditions and others killed outright, Jonathan said analysis of the video "does not really give us a conclusive position."
He said he suspected some of the hostages might still be alive because the video did not show all their bodies.
The hostages, from Greece, Lebanon, Italy and Britain, were kidnapped by members of the Ansaru faction of Boko Haram in February from a construction site in the northern state of Bauchi.
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