China's top antigraft body says the case of Zhou Yongkang has been officially handed over to Chinese judicial authorities for potential criminal prosecution.

To this point, the former member of politburo's case was being handled by the CPC's discipline department.

At the same time, the Communist Party's anti-corruption watchdog has also confirmed it's now looking into the graft allegations against former senior political advisor Ling Jihua.

The announcements have been made as part of a news conference this Wednesday, where anti-graft officials have outlined the work they've been doing as part of their year-long anti-corruption campaign.

The Party's Discipline Inspection Commission is reporting over 20-thousand officials involved in over 50-thousand different violations have received serious sanctions.

Huang Shuxian is the deputy head of the Commission.

"In 2014, as part of our work, we investigated and prosecuted a wide-ranging corruption case in the coal-rich province of Shanxi. We have also pursued accountability in a sweeping election fraud case in Hunan. This investigation included punishing 467 local officials and handing over 69 of them to judicial officials for potential prosecution."

Authorities also say they've managed to repatriate over 500 corrupt officials from overseas, collecting close to 450-million dollars in ill-gotten gains from them.