BEIJING has tightened press censorship over corruption and other ''negative phenomena'' in the People's Liberation Army (PLA). Chinese sources said yesterday both army and civilian media had been ordered to exercise extreme caution in reports about crimes and misdemeanours attributed to PLA officers and soldiers. ''The media has been discouraged from reporting on economic crimes, mainly corruption, committed by military staff,'' a source said. ''Another taboo subject is the increasing number of conflicts between PLA authorities and local units.'' It is understood such conflicts usually have to do with land-use rights, particularly the redevelopment of urban plots claimed by both military and civilian authorities. PLA units have also scaled down the number of interviews that military staff are giving to Chinese and foreign media. Such interviews now have to be cleared by senior officers having the rank of army commander. A source close to the PLA said the policy-setting Central Military Commission launched a large-scale anti-corruption campaign in August alongside a similar one organised by the civilian leadership. At least 10 officers with the rank of major-general or above were reported to have come under investigation. A few among these are believed to have been implicated in the smuggling of cars and other big-ticket items along the coast. Since autumn, however, a virtual news blackout has been imposed on the results of the anti-graft drive. The source said aside from ''protecting'' the PLA's domestic and overseas image, the censorship was aimed at preventing internal morale from deteriorating. ''Army morale has been badly affected because of frequent reshuffles after the Tiananmen Square crackdown and because of the large number of officers who have gone into business,'' the source said. ''The authorities are afraid that if stories about army corruption and other negative phenomena are widely reported in the media the PLA's recruitment problems will be worsened.'' By contrast, official media has been forthcoming with results of the four-month-old anti-corruption campaign in civil society. In the past two months detailed coverage has been given to the alleged graft-related crimes of cadres, including the police chief of Guizhou province, Guo Zhengmin; the deputy secretary-general of Hainan province, Li Shanyou, and the police chief of the Huizhou special economic zone, Hong Yonglin. The official media and the pro-Chinese press in Hong Kong have referred to these officials as ''tigers'' or big-time offenders. In the Chinese hierarchy, however, Mr Guo and other suspects featured recently in the national press are merely mid-echelon officials. Contrary to promises made in internal documents, Beijing has yet to publicise corrupt cases involving cadres of ministerial rank or above.