The UN Security Council has strongly condemned the kidnap of hundreds of Nigerian schoolgirls, as the world body’s Secretary General dispatched an envoy to help find them. The diplomatic moves came after Amnesty International said that Nigeria’s military had been warned of an attack on a school in which more than 200 girls were abducted by Boko Haram Islamists three weeks ago, but failed to act for nearly five hours. The Nigerian military denied the allegation.