THE People's Liberation Army (PLA) has warned against the ''spirit of mammonism'' corrupting combat-readiness. The warning came amid reports of army units having made new strides in the business world. In an editorial yesterday, the People's Liberation Army Daily said the socialist market economy had brought new challenges to the military. The official newspaper called for the development of ''spiritual civilisation'', a euphemism for socialist values, to ensure the quality of the nation's fighting forces. ''The tendencies of using power to seek economic gains, mammonism, going after the good life, and materialism, which exist within a minority of our society, will be reflected within the armed forces,'' the paper said. It called for the strengthening of spiritual civilisation to ''combat such negative, corrupt and ugly phenomena''. ''We must propagate revolutionary soldiers who have ideals, morals, culture and discipline.'' Socialist values the paper cited included ''the goal of serving the people whole-heartedly and maintaining the traditional spirit of the [pre-1949] Red Army''. Army analysts said soldiers' morale had hit a new low because the gap between their income levels and those of other sectors of society had widened. This is despite the fact that a sizeable portion of the recent 12.5 per cent rise in the military budget will be used to boost PLA members' pay. Meanwhile, in apparent contravention of the campaignagainst greed, PLA-affiliated companies have made new strides in the socialist market economy. The semi-official China News Service reported yesterday that ''a few tens of military-industrial enterprises'' had set up a conglomerate to invest in Hainan province. The service quoted Hainan Governor Mr Ruan Chongwu as telling the preparatory committee for the venture, tentatively named the Hainan Peace Shareholding Co Ltd, that it was particularly welcome to invest in airports, highways and tourism.