The Nigerian military has admitted that most of the 129 girls abducted by Boko Haram militants from their school in the country's restive northeast remain missing.
The military had claimed on Wednesday that all but eight of the 129 girls snatched from their school in the state of Borno managed to escape, contrary to the position of the state government and the school principal.
"The defence headquarters wishes to defer to the school principal and governor's statement on the number of students still missing," defence ministry spokesman Chris Olukolade said in a statement on Friday.
He said that vigilante groups and hunters were assisting the authorities in the frantic search for the girls, who were grabbed from the Government Girls Secondary School in the Chibok area of Borno state.
Up to 20 girls are thought to have escaped.
"We have recovered about 20 girls now and they are with us. After they escaped, the girls went to village heads who live close to where they found themselves and the local leaders brought them to us," Mallam Inuwa Kubo, Borno's education commissioner, said on Thursday.
The mass abduction on Monday sparked global outrage and came just hours after the deadliest attack to hit the capital Abuja, where a bomb blast also blamed on Boko Haram killed at least 75 people.
Boko Haram's extremist uprising, aimed at creating a strict Islamic state in northern Nigeria, has killed thousands since 2009.
Parents of the missing girls swarmed the home of Chibok's tribal chief early on Thursday, demanding answers after the military claimed the girls were free, residents said.
Others decided to scour the remote area in a desperate search for girls who may have escaped.
Boko Haram's name loosely translates as "foreign education is forbidden" and the group has repeatedly attacked schools and universities.
Students have been massacred in their dormitories and bombs set off at university campuses, but the mass abduction specifically targeting girls is unprecedented.
Borno's governor has offered a 50 million naira ($A321,200) reward to anyone with information leading to the return of the schoolgirls.
President Goodluck Jonathan met with security chiefs on Thursday to review the unrest.
Another security meeting has been slated for next week.
Violence by Boko Haram has cost more than 1500 lives already this year, the deadliest stretch in the five-year uprising.
