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By James Pomfret
ZENGCHENG, China, June 13 (Reuters) - Riot police poured into a southern Chinese factory town crowded with migrant workers on Monday, a day after militia fired tear gas to quell rioting over the abuse of a pregnant street hawker who became a symbol of simmering grassroots discontent.
Video footage and photos shot on mobile phones by residents in Zengcheng in Guangdong province showed angry mobs torching government buildings, smashing police vehicles, and clashing in their thousands with riot police over the weekend.
The unrest was triggered by security guards who had set upon the hawker, Wang Lianmei, on Friday, but underlying frustration at other building social pressures including rampant food price and housing inflation, as well as corrupt local officials, had also stoked anger amongst many locals.
By its latest count, China has about 145 million rural migrant workers. Though many of them have gained better wages and treatment in recent years, the gap between them and established urban residents remains stark, feeding ire about discrimination and ill-treatment. A pregnant stall holder set upon by guards would embody that resentment in the eyes of many migrants.
Footage showed riot police firing tear gas and deploying armoured vehicles to disperse the crowds, as well as handcuffing protesters.
By Monday evening the city was calm but tense with the mass mobilisation of several thousand riot police, most equipped with shields, helmets and truncheons, while a small number were armed with tear gas guns. Hundreds also marched in formation through the streets and chanted in a massive show of force.
"There were thousands of people on the street (last night), it was chaotic," said a shirtless migrant worker from Chongqing surnamed Li, as he squatted and watched the police lines with a group of friends. "But there are a lot more police tonight."
Though protests have become relatively common over anything from corruption to abuse of power, the ruling Communist Party is sensitive to any possible threat to its hold on power in the wake of the protests that have swept the Arab world.
Despite pervasive censorship and government controls, word of protests, along with often dramatic pictures, spreads fast in China on mobile telephones and the Internet, especially on popular microblogging sites.
"Tonight probably no one will dare come out," wrote one blogger on a local Zengcheng chatroom on the QQ social networking website, referring to the huge security deployment, while a stream of images of street scenes streamed in.
"REVENGE AGAINST SOCIETY"
Guangdong is also a pillar of China's export industries, and persistent unrest there could unnerve buyers and investors. Zengcheng is a major garments and denim export hub, while Japanese carmaker Honda runs its major Guangzhou car manufacturing facility several kilometers away.
Witnesses said more than 1,000 protesters had besieged at least one government office in Zengcheng.
News reports said the incident was sparked on Friday night when security personnel in nearby Dadun village pushed pregnant hawker Wang, 20, to the ground while trying to clear her from the streets.
"The case was just an ordinary clash between street vendors and local public security people, but was used by a handful of people who wanted to cause trouble," Zengcheng Mayor Ye Niuping was quoted as saying by the China Daily newspaper.
Other clashes have erupted in southern China in recent weeks, including in Chaozhou, where hundreds of migrant workers demanding payment of their wages at a ceramics factory attacked government buildings and set vehicles ablaze.
Last week, protests erupted in central China at the death under interrogation of an official.
Over the weekend, state media said two people were slightly injured in an explosion in Beijing's neighbouring city Tianjin, set off by a man bent on "revenge against society."
In 2007, China had over 80,000 "mass incidents," up from over 60,000 in 2006, according to the Chinese Academy of Social Sciences. Many involved no more than dozens protesting against local officials over complaints about corruption, abuse of power, pollution or poor wages.
No authoritative estimates of the number of protests, riots and mass petitions since then have been released.
Guangdong's Communist Party boss, Wang Yang, is one of the ambitious provincial leaders who may win a place in China's next central leadership, after President Hu Jintao and Premier Wen Jiabao retire from power from late next year.
In past months, Wang has sought to cast himself as a moderate leader willing to heed ordinary citizens' gripes, and has said his priority is improving the public sense of wellbeing -- a gentler message than the hardline one that domestic security officials have pushed. (Additional reporting by Xavier Ng, and Chris Buckley in Beijing; Editing by Ben Blanchard and Daniel Magnowski)