International efforts to find and rescue more than 200 kidnapped Nigerian schoolgirls are facing "large information gaps", according to the UK experts who have started work to tackle the crisis.
The UK advisory team said it was still trying to establish who was missing, after spending its first 24 hours in the capital Abuja in talks with senior officials including Nigerian president Goodluck Jonathan.
The Nigerian government has been heavily criticised at home and abroad for being slow to react to the kidnapping of the 276 girls on 15 April.
The UK's Ministry of Defence has already linked up with the Nigerian military, including the force which has operational control of the region where the kidnaps took place.
The Nigerian military has flown more than 300 sorties in the hunt for the abducted schoolgirls, a Major has told ITV News' Rageh Omaar.
A newly released video from Boko Haram reportedly shows the kidnapped Nigerian schoolgirls.
The man who started a viral hashtag campaign in support of the kidnapped Nigerian schoolgirls says it has forced the government to act.