(ICC) – An influx of ethnic Montagnards from Vietnam to Cambodia over the last few months is creating a difficult challenge for the United Nations High Commissioner for Refugees, a humanitarian group reported last Friday. However, Refugees International says that the refugee flow should also generate international pressure on Vietnam to change policies that are causing the mostly-Christian Montagnards to flee to Cambodia . Montagnard hill tribes in Vietnam have long encountered discrimination from Hanoi , the Washington, D.C.-based group said in a statement released last Friday. Many of them helped the U.S. during the Vietnam war. They are Christians in a communist country. Their native lands have been targets of Vietnamese development plans to increase the production of coffee and other crops. They are an independent force in a land of discipline and central direction. Refugees International reported that the harassment that many Montagnards face in Vietnam has prompted them to flee across the border to Cambodia , and the refugee flow will continue until Vietnam ends its oppressive policies.