Nigeria aims to have around 200 schoolgirls kidnapped by Islamist group Boko Haram freed by Tuesday.

Authorities said they had agreed a ceasefire with the militant group to make the release possible.

Boko Haram kidnapped more than 200 girls at gunpoint from a school in Chibok, northeastern Nigeria, on April 14th.

Some of the girls managed to escape from the group in the aftermath of their kidnap or during fighting among militants, but the vast majority are still missing.

Members of the Bring Back Our Girls campaign said in a tweet: "We are monitoring the news with huge expectations."