Christians are being asked to pray after Boko Haram threatened to execute a Christian schoolgirl at the of the month unless the Nigerian government meets its demands.
Leah Sharibu was one of 110 schoolgirls kidnapped by the terrorist group from their school in Dapchi, north-eastern Nigeria, in February this year.
It was reported last month that while the others had been released, the group was continuing to hold Sharibu, 15, because she refused to deny her Christian faith. Audio was also released in which Sharibu pleaded with the Nigerian government to help free her.
However, she remains in captivity and there are fears for her life after Boko Haram threatened to execute her if its demands for further ransom payments are not met.
Release International said her life was in 'immediate danger' as it called on Christians to pray that she and others being held captive by Boko Haram would be released unharmed.
Fears for Sharibu intensified after Boko Haram executed Saifura Khorsa, an aid worker with the International Committee of the Red Cross, who was abducted by the group earlier this year.
ECWA, the church that Sharibu and her family belongs to, has spearheaded a prayer campaign for Sharibu's release.
Christian Solidarity Worldwide is encouraging Christians to support the prayer call by praying every day at 5:30pm, the time Sharibu was abducted.
CSW called on President Muhammadu Buhari to negotiate the release of Sharibu, the two remaining humanitarian workers, and 112 abducted schoolgirls from Chibok who are still in captivity.
It also asking Christians to sign an online petition to the Nigerian High Commissioner asking that it raise concerns about her welfare with the Nigerian government.
Earlier this month, CSW held a 200-hour protest against Sharibu's continued captivity outside the Nigerian High Commission in London.
The organisation said: 'We've seen incredible answers to prayer in the past and we certainly need one now.'