Guangdong's Communist Party disciplinary authorities are investigating a possible collaboration between Dongguan police officers and the city's biggest underground casino after a raid there last month. As illegal casinos need the protection of police and officials to operate, Ding Shoujun, the police chief of Dongkeng town, was dismissed along with three subordinates this month. The casino's owner is still at large, state media reported, and party disciplinary authorities believe more senior cadres probably took bribes and provided protection to the operator. Guangdong officials said the public had often complained about the casino, and repeatedly tried to warn the township police during the three years of its operation. Some tip-offs named the casino and gave its full address in 2007, but no clampdown took place. The party disciplinary watchdog will investigate whether Dongguan police were negligent in their duties. For his part, Ding said he was just a scapegoat. 'I've wanted to crack down on underground casinos since my transfer to Dongkeng in 2005,' The Southern Metropolis News quoted Ding as saying in a report published on Wednesday. 'But I was unable to do that [because of the protection]. 'I feel relaxed after being removed from my post ... Police can clean out the gambling in this town by taking this opportunity. It would be a good deed for the community.' Ding's successor, Tian Guangqing, vowed to close all casinos even though he and other police officers could face revenge from the owners. 'We will crack down on all gambling venues no matter who the backstage supporters are and whether the campaign costs us our jobs,' he said. The casino's operator is believed to be linked to the owner of a nearby luxury hotel and a huge entertainment venue who leased the land and a residential building in which the casino is located. The owner is believed to be a Dongguan native who had built a relationship with cadres and police at provincial and city levels. Guangdong's committee for discipline inspection said it had secretly filmed all staff and gamblers in two visits to the casino in September.