By Abdoulaye MassalakiNIAMEY (Reuters) - Thousands of civilians fled their homes in the southeastern Niger town of Diffa this week, officials said on Thursday, following waves of cross-border raids and suicide bombings by Nigerian militant group Boko Haram.Attacks in Niger are deepening a humanitarian crisis in the remote border zone. The area, struggling to feed some 150,000 people who have run to escape violence in northern Nigeria, has seen around 7,000 arrive this week in Zinder, Niger's second biggest town some 450 km (280 miles) west of Diffa.The International Rescue Committee, which supplied the population estimates, has teams working on the ground there. Matias Meier, country director, said some families in Zinder, one of the poorest regions in Niger, were having to host 20 people, while other displaced were sleeping in the stadium.Still more continue to make the journey from Diffa, he added."Those who went on the trucks are the lucky ones. Bus tickets are sold out until the end of next week. Many are just walking or going by bicycle," Meier told Reuters.Boko Haram's insurgency has killed thousands in northeastern Nigeria. Regional armies are mobilizing a joint force of 8,700 men to defeat the group that is increasingly threatening neighboring countries.Niger's military says its army, backed by Chadian forces deployed to the country, has killed hundreds of Boko Haram fighters in several battles sparked by raids in the Diffa region by militants this week.Local authorities in Zinder told France's RFI radio that at least 4,000 displaced had arrived in the town.Authorities in Niger have registered over 100,000 Nigerian refugees and Nigeriens who have returned to their home country from Nigeria. However, Meier said violence in recent months meant the number of displaced in Diffa region was closer to 150,000.The new wave of displacement comes as farmers should be preparing to plant crops for the next harvest, highlighting the long-term impact of the violence."People should be planting now but they are on the move," Meier said.(Writing and additional reporting by David Lewis; Editing by Sophie Walker)Join the conversation about this story Click here to read full news..