International security experts are arriving in Nigeria as efforts to rescue more than 270 missing schoolgirls are ramped up. <br /><br />The military has rejected accusations that it was tipped off hours before Boko Haram kidnapped the girls.<br /><br />Nearly a month after they were taken, more than 270 are still missing. <br /><br />The Nigerian government has been criticised for being too slow to respond, and for rejecting earlier offers of international help.<br /><br />Al Jazeera's Rawya Rageh reports from Abuja.
