BEIJING has quietly boosted military subsidies, which are not reflected in the official budget of the People's Liberation Army. Over the past few years, China's top brass have reassured foreign leaders that the PLA budget had only had modest increases. But figures quoted by the PLA do not take into account hidden but very substantial subsidies by government units and state factories. In a series of articles celebrating the 67th anniversary of the founding of the PLA today, the official media revealed that governments at various levels had devoted extra resources to subsidise military supplies and speed up the demobilisation process. PLA units have been accorded various preferential policies under the campaign titled: ''Support the Army and give superior treatment to their relatives.'' The People's Daily reported yesterday that ''a great majority'' of provinces and cities had drafted measures to ensure the quantity and quality of grain and other foodstuffs for the Army. It is understood that in many instances, PLA units are able to get priority supplies at subvented prices. Areas including Fujian, Hainan, Tibet and Xinjiang have helped army units start a so-called ''vegetable basket engineering project'', so that, the People's Daily said, ''the livelihood of the garrisons will improve at a time of major fluctuations in market prices''. More than 30 large cities have introduced preferential policies in job placement for demobilised staff. More than 58,000 PLA rank and file, together with 25,000 of their relatives, were successfully relocated last year. The official press reported yesterday that open cities, including Guangzhou, Shenzhen, Zhuhai, Foshan, Fuzhou, Xiamen, Yantai and Qingdao had made contributions to improve PLA facilities. The improvements were in the areas of transport, communications, the construction of barracks as well as ''living conditions'' and general welfare. Many provinces and cities have passed local laws to help soldiers and their families in the areas of education and employment, and loans for setting up businesses. The five northwest provinces alone have introduced 270 such laws. Sources close to the Army said they were surprised by the generosity shown to the PLA by government units. They said the preferential policies went against the trend of obliging military units to abide by the norms of the ''socialist market economy''. The sources said the special treatment had also made it difficult for state factories to make the transition to the market place. Many such factories, anxious to lay off superfluous labour, were obliged to absorb ''quotas'' of demobilised soldiers. Cadres in the open cities have privately complained about having to make extra contributions to the Army. Western military analysts said that under the campaign, a number of ministries and departments were expected to finance more military research and development projects.