Nigerian police say peaceful rallies to demand the release of more than 200 schoolgirls seized by Islamist militants will be allowed, after earlier banning them.

But campaigners were warned to exercise caution during protests.

Abuja police commissioner Joseph Mbu said the rallies were “now posing a serious security threat”.

Nigeria has seen almost daily rallies calling for the government to take firmer action to rescue the girls.

Boko Haram militants snatched the girls from the remote Chibok village near the Cameroon border on 14 April.