Nobel peace laureate Malala Yousafzai on Monday criticised Nigerian and world leaders for not doing enough to free 219 schoolgirls kidnapped a year ago by Boko Haram. “In my opinion, Nigerian leaders and the international community have not done enough to help you,” she said in a letter to the teenagers, on the eve of the first anniversary of their abduction. “They must do much more to help secure your release. I am among many people pressuring them to make sure you are freed,” she added, calling the girls “my brave sisters”.