N'Gagam - "Sai wahala!" - in Hausa means "there's big trouble" - exclaims Zara Moustapha, living with more than 12 000 displaced Nigeriens and refugees from Nigeria in the N'Gaman desert camp in southeast Niger."There's the heat, nothing to eat, no clothes, no right to leave the camp - it's a little hell on earth," says the mother from Mallam Fatori in northwest Nigeria, a battleground between the army and the jihadists of Boko Haram, notorious for their atrocities.Seated on a mat laid on the burning sand in an improvised shelter, the United Nations' new chief of humanitarian affairs and emergency relief, Mark Lowcock, listens to the grievances of camp residents who fled their homes or were forcibly evacuated.Moustapha is among 7 000 Nigerian refugees living alongside 5 500 Niger nationals in a big shanty town of tents and shacks because of the Boko Haram insurgency, which has claimed at least 20 000 lives since 2009.Women wearing multicoloured veils and some with pierced nose jewellery came to meet the UN envoy, protected by elite troops in the camp which has already been attacked by the jihadists who frequently infiltrate the site. 'See with their own eyes' "We spoke to him about our troubles: lack of medical care, insufficient food and drinking water, insecurity and idleness," camp spokesperson Yagana Cheffou says. "We need ambulances, water of decent quality and more security. We haven't received any food aid for at least ten months," adds Boulama Mamane Ibrahim, the chief of Bande village in Niger, whose faded traditional robe billowed around his body.Because of "the bad quality of the water", an outbreak of hepatitis E had killed several people, including "pregnant women," Ibrahim says."Men, women and children sleep out in the millet fields, infested with mosquitos. There is already an upsurge of malaria," protests the chief."I have listened to their story and I shall tell it myself" in making a case to the UN General Assembly at the end of September, Lowcock, sweating profusely, pledges."If the donors don't respond, I shall tell them to come and see with their own eyes," adds the official, who stepped down as Britain's foreign aid chief in May after heated criticism of alleged profligate spending on dubious targets.Lowcock nevertheless praised international mobilisation that "has saved the lives of millions of people" in the region."Aid is insufficient, that's true," says Niger's Minister of Disaster Management Lawan Magadji, who hopes that Lowcock would raise the "400 million dollars" needed to cover humanitarian assistance "in the whole of the Lake Chad basin." Damaging 'security measures' The basin around the lake is a substantial area where the borders of Chad, Cameroon, Niger and Nigeria loosely meet. All four countries have been attacked by the Boko Haram Islamist extremists from northwest Nigeria.In Diffa, a southwest Niger border town in the basin, some 300 000 refugees and displaced people are made more vulnerable because of "security measures" taken by the authorities, according to several non-governmental organisations (NGOs).In a bid to quash incessant attacks and infiltration, the authorities have evacuated some areas, banned trade in fish and pepper and shut down the markets.Such moves have undermined the local economy at a time when Diffa has already faced repeated food crises.The region has been calm for two months, but the army remains on alert. Visiting N'Gagam, Diffa's governor Mahaman Laouali Dandano spoke up about "the presence of Boko Haram infiltrators" in the camp."Soldiers, aid workers, health staff ... everyone is putting their lives at risk to help you, yet you find it normal not to denounce these people," the governor complains to camp residents."They (Boko Haram) get supplies at the market in N'Gagam. Some even come back (from Nigeria) to visit relatives right before your eyes," Dandano protests."The BH have informers everywhere around here," chief Boulama tells AFP later. "If you denounce them, they will come to burn your houses and kidnap our children."