A prayer vigil was held outside the Nigerian High Commission in London on Tuesday to mark the 16th birthday of a Christian schoolgirl being held by terrorist group Boko Haram. 

Leah Sharibu was one of over a hundred schoolgirls abducted by Boko Haram offshoot the Islamic State West Africa Province in February last year. 

The other girls were released a few weeks later but Leah, who was 14 at the time, continues to be held hostage by the group after she refused to renounce her Christian faith. 

In addition to the prayer vigil in London, a special service was being held in Leah's honour at the Nigerian headquarters of her church's denomination, the Evangelical Church Winning All (ECWA), while the US Senate in Washington DC was to hold a cake cutting ceremony.

The prayer vigil was joined by David Linden MP, who has written to Prime Minister Theresa May asking her to put pressure on the Nigerian government over Leah's continued captivity. 

Writing on Twitter ahead of the protest, Mr Linden MP said: "As it happens, I share a birthday with Leah Sharibu.

"The difference is, I will get to spend my birthday as a free person whilst Leah remains in captivity. We must continue to press the Nigerian Government for action on this."

His letter also calls for the release of other hostages being held by the group, including over a hundred schoolgirls kidnapped in Chibok in 2014 who are still missing.  

Boko Haram has in the past threatened to kill Leah.  It didn't go through with the threat but did kill another female hostage and said that Leah and fellow hostage, Alice Ngaddah, would remain with the group as its slaves for life.

CSW's Chief Executive Mervyn Thomas appealed to the Nigerian government to secure Leah's freedom.

"She has been held by this violent group for over a year now, waiting for the government which negotiated the release of her colleagues to secure her release," he said.

"CSW calls on the Nigerian government to act on its promises and move decisively to secure the release of Leah Sharibu, Alice Ngaddah, and the 112 girls who were kidnapped from their school in Chibok in April 2014."