– 7: US First Lady Michelle Obama tweets a picture of herself with a sign reading #BringBackOurGirls, joining the social media campaign that has also attracted politicians, actors and other prominent public figures such as Pakistani eduction activist and Nobel Peace Prize laureate Malala Yousafzai and CNN star anchor Christiane Amanpour.

– 9: Amnesty International claims that Nigeria’s military was warned of the school attack but failed to take action due to lack of manpower. The military denies the allegation.

The UN Security Council strongly condemns the mass kidnappings which it says “may amount to crimes against humanity” under international law.

– 10: British, French and US experts provide help for the search operation. China and Israel also offer assistance.

– 12: Boko Haram releases a new video showing about 100 of the missing girls, alleging that the teenagers have converted to Islam and will not be released until militant prisoners are freed.

– 17: Nigeria and its neighbours Benin, Chad, Cameroon and Niger vow to work together to fight Boko Haram in what Cameroon President Paul Biya describes as a “declaration of war”.

Some os the Chibok schoolgirls captured in April

– 21: The United States deploys 80 military personnel to Chad to help regional efforts to rescue the schoolgirls.

– 26: Nigeria’s highest ranking military officer, Chief of Defence Staff Alex Badeh, says they have located the missing teenagers but warns a rescue operation would put their lives at risk.