A new video appearing to show some of the 219 Nigerian schoolgirls who were kidnapped by Islamist group Boko Haram more than two years ago has sparked fresh outrage at the fact they have still not been rescued.

Abducted from a school in Chibok by armed gunmen on April 14, 2014, the missing schoolgirls are known to have been forced from their dormitories onto trucks and driven into the bush.

Here we take a look at the some of the key moments in the timeline of events surrounding their disappearance.

Boko Haram seize 276 girls from the Government Girls Secondary School in Chibok as they gather for science exams. Some manage to escape, jumping off pickup trucks as the Islamic extremists drive them towards the Sambisa Forest but hundreds do not.

The #BringBackOurGirls viral campaign kicks off after an audience member at a speech by the former Nigerian minister Obiageli Ezekwesili tweets out the message in a public appeal to the government to do something to find the missing girls.

The families of the missing schoolgirls protest over a perceived lack of action by authorities as the government and military face mounting criticism from many who say it should be doing more to get the girls released.

Nigerian police offer a £175,000 reward for information that leads to the rescue of the missing schoolgirls.

A video released by Boko Haram reportedly shows the kidnapped Nigerian schoolgirls. It also shows the rebel group's leader stating he will release the girls in exchange for prisoners.

Nigerian president Goodluck Jonathan rejects an offer from Boko Haram to exchange the schoolgirls it abducted for jailed militants, it has been confirmed.

Nigeria's President Goodluck Jonathan cancels his first visit to the village from which the girls were taken amid 'security fears'.

Four girls kidnapped by Boko Haram militants escape their captors leaving the number of still missing at 219, according to the education commissioner for Nigerian Borno state Chibok.

First new video footage of missing girls is released showing 15 of the girls in black robes identifying themselves as the pupils abducted from the school two years ago.