The federal government said it continues the negotiations with Islamic State West African Province (ISWAP), a breakaway faction of Boko Haram, about Leah's release.
The statement said: "Lines of communications remain open with the kidnappers, ISWAP, to secure the release of Leah Sharibu. Contrary to false reports, she is alive – [we have been] given assurances by our security agencies – and the government is committed to her safe return, as well as all other hostages to their families."
Leah was abducted along with over 100 of her classmates from the Government Girls Science and Technical College in Dapchi, Yobe state, on 19th February 2018.
While the others were released within a month, Leah, the only Christian in the group, remains in captivity as she was ordered, but refused, to give up her faith.
In October 2018, ISWAP announced that it will keep Leah as a slave for life.
UK Christian charity Open Doors, which supports persecuted Christians, said it's shameful Leah still hasn't been rescued, but the update brings some hope.
Dr Matthew Rees, Head of Advocacy at Open Doors UK and Ireland, said: "Leah Sharibu was kidnapped because she is a girl and held captive because she is a Christian. She embodies the incredibly vulnerable position of Christian women in northern Nigeria.
"It is outrageous that Leah remains in captivity, abused as a PR tool and negotiating pawn by Boko Haram. However, the government's assurance that it will make more efforts to secure her release is encouraging."
The president's spokesperson said in the statement that the government is pursuing many options to ensure Leah's release committing to law and communication and using the strategies at their disposal such as legal initiatives and the use of the latest hostage negotiation techniques.
"Kidnapping for ransom should never be encouraged. This means not capitulating to the demands of terrorists and refraining from rewarding their heinous crimes with payment," the statement said.
In October 2018, for the first time since Leah's capture, President Buhari addressed Leah's mother via Twitter: "Today I spoke with Mrs Rebecca Sharibu, to reiterate our determination to bring her daughter Leah back home safely.
"The thoughts & prayers of all Nigerians are with the Sharibu family and the families of all those still in captivity. We will do everything we can to bring them back," he said.
Nigeria is number 12 on the 2019 World Watch List, Open Doors' annual ranking of the 50 countries where Christians face the most extreme persecution.
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