The Christian Association of Nigeria on Saturday increased its estimate of the number of students and teachers abducted from a Catholic school on Friday to 315 from an earlier estimate of 227.
The association said a verification exercise had found that a further 88 students had been captured after they tried to escape.
"This now makes it 303 students (and) ... 12 teachers, bringing the total number of abducted persons to 315," it said in a statement.
Nigeria's security situation has been under heightened scrutiny since US President Donald Trump threatened military action in the West African country over the treatment of Christians.
Nigeria's government says Trump's claims that Christians face persecution in Nigeria are a misrepresentation of the country's complex security challenges.

Explosion hits US embassy in Oslo, causing minor damage, thick smoke
Four killed in Beirut hotel strike, Israel says it targeted Iranian commanders
Drone attacks cause major fire at Kuwait International Airport
Israel warns Lebanon of 'heavy price' as week's death toll nears 300
Trump rejects settling war with Iran
Qatar intercepts 6 ballistic missiles, 2 cruise missiles
Trump tells Britain he does not need its help to win Iran war
Israeli settler fatally shoots Palestinian in West Bank
