The Education for Nature Vietnam ( EVN), a Vietnamese non-government organization committed to environment conservation, said here on Monday that illegal hunting and trading have seriously diminished tiger population in the country. The demand for tiger bones for medical purpose has reduced the number of tigers in Vietnam and neighboring countries, said Nguyen Thi Van Anh, coordinator of an EVN program for wildlife protection at a press conference here. In Vietnam, there are some tiger farms where tigers are raised and sold to domestic and overseas markets to make medicines. The medicine is believed to strengthen human bone, improve health and treat other diseases. EVN said it has found out the links between some tiger farms and the illegal trading, and an overall picture or cross-border tiger trading. Illegal tiger trading is not only a problem for Vietnam, but also an international issue, said Anh. Vietnamese agencies should coordinate with relevant agencies in Laos, Cambodia and Thailand and other countries in investigating and prosecuting criminal gangs of illegal tiger trading, said Anh. 