Reports from aid workers recently released from captivity in Nigeria suggest missing teenager Leah Sharibu is alive and well.

One of the captives, released by the Islamic State West African Province (ISWAP) faction of Boko Haram last week, Jennifer Ukambong Samuel told local media that while she had not seen Leah, she had been told by another woman who had been kidnapped that she is being held in an undisclosed location.

Sharibu was among 110 schoolgirls kidnapped in Dapchi, Yobe state in February 2018.

While her classmates were released, she was kept behind as she refused to convert from Christianity to Islam.

News of her wellbeing will be welcomed by those who've been praying for her release as disputed reports last year suggested she had been killed by her terrorist captors.

Religious freedom charity Christian Solidarity Worldwide has been campaigning on her behalf.

Chief executive Mervyn Thomas said: "We are encouraged to hear that Leah Sharibu, Alice Ngaddah and Grace Taku (other captives) are alive and well; however, it is important to remember that they are still in the hands of a highly dangerous and violent terrorist group. 

"We continue to call on the government of Nigeria to do everything in its power to secure their immediate release, and urge the UK government to raise this case with President Buhari as they meet with him today for the UK-Africa Investment Summit. 

"In addition, the current levels of insecurity in Nigeria are both a disincentive to investment and inimical to development.  

"Therefore, we ask the UK government to raise the continuing deterioration in security, which is particularly marked in Kaduna State, and to impress upon the president the urgent need to protect every vulnerable community regardless of creed or ethnicity, to ensure the return of all abductees and to facilitate the stability necessary for sustainable investment."