When Al-Qaeda swept into Yemen\'s southern Abyan province a year ago, thousands of local residents ran for their lives. Today, the United Nations says more than 160,000 of them are scattered in towns and cities across Yemen\'s south, languishing in miserable living conditions and surviving on the hope that one day soon they will return home. That prospect, however, is increasingly unlikely as Yemeni government forces battle to oust Al-Qaeda from Abyan, forcing hundreds more to flee the region each month. Abyan towns and cities have been hit by air raids and ravaged by fierce fighting as the army tries to wrest back control of territory, stoking fears among the displaced that what they left behind may already be destroyed. International aid organisations, under-funded and overstretched, are struggling to cope with the growing needs of the families who left their homes with little more than what they could carry. \"We have nothing left,\" said Arwa, a mother of two who escaped from the city of Jaar after Al-Qaeda took control. She now lives in the science lab of Al-Masmoum public school in the southern port city of Aden. She shares the space with her husband, their two children and another family of three. Between the seven of them, they have five mattresses, taking turns sleeping on the bare classroom floor. They wash up and do the dishes in the sinks once used for lab experiments and complain that the UN food rations they receive are not enough. When Arwa\'s 8-year-old daughter and 14-year-old son both fell sick, she sold the soap given to her by aid agencies to buy medicine. \"This is no way to live,\" she sighed. Arwa\'s family is relatively lucky. They are only seven people to a classroom. In most of the 78 schools in Aden that the displaced now call home, as many as four families share a single classroom. They have no privacy and often live with strangers. Some of the newest arrivals have been forced to seek shelter on school grounds or in the hallways. \"They are living in very difficult conditions. This is the case in all the schools,\" said Sara Sulieman from the international aid organisation Oxfam. In total, there are over 535,000 Yemenis displaced by past and current conflicts in the country\'s north and south. Only a limited number have so far been able to return home and most still rely on international aid to survive. The displacement crisis is further compounded by Yemen\'s already dire humanitarian problems, a consequence of decades of under development, poor governance and rampant corruption. \"The situation is really grim,\" said Alison Parker of the UN children\'s fund, UNICEF. There are \"huge gaps\" in the assistance and aid needed. In Aden, where most of Abyan\'s 35,000 displaced families now live, the \"biggest problem\" is shelter, according to Tareq Talahma from the UN\'s Organisation for the Coordination of Humanitarian Affairs (OCHA). Some rent rooms with their measly government incomes. Others have moved in with relatives or settled in abandoned buildings. About 20,000 IDPs live within the grounds of Aden\'s public schools, preventing thousands of children from attending classes. The local \"kids are going to school in three shifts,\" said Talahma, cautioning that the situation is causing \"huge tensions\" with the host community. At Al-Masmoum, one building has been designated for students, while the other two are used as living quarters for the displaced. The classrooms are crammed with as many as 50 students, often two per desk. The quality of education has been severely compromised and the schools have suffered major physical damage. According to UNICEF, Aden\'s IDP housing crisis has disrupted learning for over 100,000 students, many of whom have already lost all or most of the 2011-2012 academic year. Conditions for displaced children are even worse. According to Sulieman from Oxfam, most of them don\'t receive an education at all. Meanwhile, only three months are left before the next academic year begins and there is no solution in sight. \"There is no clear vision\" on where to house the displaced if they are evacuated from the schools, said UNICEF\'s Parker. Much of the delay is a result of an ongoing dispute between Aden\'s governor who insists on transferring the IDPs to specially set-up camps and the UN which is reluctant to do so. \"It\'s not an option,\" said Talahma. \"In the case of Aden, camps are a lethal recipe ... and will only add to existing tensions.\" The uncertainty is taking its toll. \"What we crave is some safety and some security ... Can\'t the rest of the world help us with that?\" asked 37-year-old Nimah Mansur, who fled Abyan last year but for whom there are no empty classrooms to house her family. She lives in a UN tent in the school\'s playground with two other families. In the sweltering heat of the summer months, they are forced to spend most of the days outside as temperatures inside the tent become unbearable. \"We can\'t breathe in here,\" said Mansur. \"When can we go home?\"