HONG KONG (CNN) -

Three more officials have been given the chop as part of China's anti-corruption drive. The disgraced politicians are the latest in a string of purges of former aides to Zhou Yongkang, China's retired chief of domestic security, fueling speculation that Zhou will eventually face charges.

Ji Wenlin, former deputy governor of Hainan, and Yu Gang, former senior official in the Politics and Legal Affairs Commission, have both been expelled from the Communist Party for taking "huge bribes" and committing adultery, announced the Central Commission for Discipline Inspection (CCDI) on Wednesday.

Adultery, while not illegal in China, is considered a serious violation of Party regulations.

The third official charged with corruption is Tan Hong, a former senior officer in the Ministry of Public Security.

All three have close ties to Zhou, working under the security czar at some point during their careers. Zhou was a former member of the Politburo Standing Committee, China's top decision-making body, until he retired in 2012. He was considered one of the most powerful men in China, serving as the head of China's security and police institutions.

Rumors surrounding Zhou's downfall have been circulating on China's social media for two years, gaining momentum in recent months as high-profile corruption probes have led to the detention of senior officials linked to him throughout his career. Zhou would become the highest-ranking official ever to face corruption charges in the history of the People's Republic.

But there has been no official announcement of an investigation into Zhou. Reuters has reported sources saying Zhou is now under house arrest.

Netted 'tigers'

In 2013, some 182,000 officials were disciplined while courts nationwide tried 23,000 corruption cases, according to the CCDI.

After coming into power in late 2012, President Xi Jinping banned official extravagance -- from banquets to year-end gifts -- and vowed to target "tigers and flies" alike in his fight against corruption when describing his resolve to spare no one regardless of their position.

On Monday, one of the biggest "tigers" met his downfall: Xu Caihou, former vice chairman of the Central Military Commission that runs the world's largest standing army, and a former Politburo member, was found to have accepted bribes.

Longtime China observers, however, point to the limits of President Xi's war on corruption.

"Corruption is so widespread and so endemic that campaigns are just not going do it," said Frank Ching, a Hong Kong-based commentator and columnist on Chinese politics. "Something has to be done about the system."

"There have been public calls for a law to require officials disclosing their assets. There has been no indication that they are going to do that. In fact, a number of people calling for this law have ended up in prison," he added.

"I think people will be much more convinced of the seriousness of this anti-corruption campaign if there were a move to enact such a law."