If the People's Liberation Army kept the Communist Party in power in 1989, the police have kept it in power since. It is the police in their dark blue uniforms - aided by the People's Armed Police - who every day stand in the front line and confront farmers angry over the loss of their land and poisonous factories, urban workers demanding unpaid wages, and city residents who want larger compensation for the loss of their homes. Many have paid the ultimate price. According to the Ministry of Public Security, 431 police were killed in the line of duty last year. Last August, it said 10,768 had been killed on duty and 151,468 injured since 1949. The government owes them an enormous debt. The ministry's website does not give the number of the force but shows the size of its empire - including the frontier police and immigration control, and the fire service - policing the aviation industry, railways and national forests, and fighting drugs and economic crime. The sprawling headquarters it shares with the Ministry of State Security is a symbol of its size and importance - overlooking Changan Avenue on the northeast corner of Tiananmen square, opposite the Forbidden City. As a reward for this key role in maintaining social stability and keeping the party in power, the government gives the police force a substantial budget and great privileges. One lesson of 1989 was that it lacked the sophisticated crowd control equipment common to forces in developed countries. That has long been remedied. Highly equipped riot police are on 24-hour duty in cities and county capitals across China. Police are well paid, well fed and well housed. Governments at all levels have 'stability funds' and spend most of it on the security forces during times of conflict. The police units that monitor the internet have the best equipment and software money can buy. Critics say that the use of the police alone is not enough to ensure social stability. A research report published this month by Tsinghua University argued that China did not have proper channels for protest. 'When fierce social protests occur, some local governments quickly put the police in the front line. This does not help to ease the conflict but adds fuel to the fire and leads to a confrontation between the people and the police ... government departments politicise conflicts and turn them into issues of ideology, elevating them into an attack on the system itself and social stability,' it said. Local governments invoke a 'threat to social stability' to justify their actions. The report said that while conflicts over politics, religion and ideology could not be negotiated, conflicts over interests and benefits could be discussed and a compromise reached. It called for governments to set up new channels to resolve such conflicts and train staff with expertise in this area.