China's state television broadcaster has deleted an online posting made, it claims, by hackers.
The message, posted late Monday on CCTV's English-language Twitter account, said President Xi Jinping "has set up a special unit to investigate corruption allegations against the retired leader Zhou Yonkang."
CCTV deleted the posting about two hours later.
On Tuesday, the broadcaster said someone hacked into its Twitter account and used it to "illegally post incorrect information copied from other sources." It did not elaborate.
Unconfirmed foreign media reports have been circulating for weeks indicating that the 70-year-old former domestic security chief was under investigation for corruption.
There have also been signs that Zhou remains politically active, including his attendance at public events and the appearance of his name in state media outlets.
Zhou was a member of the elite Politburo Standing Committee, China's highest governing body, from 2007 to 2012. He also oversaw China's sprawling state security apparatus.
If such an investigation were to take place, it would be the first time in decades the party has investigated economic crimes by a former or current Standing Committee member.
Zhou is a close ally of disgraced former Politburo member Bo Xilai, who has been sentenced to life in prison for taking bribes, embezzlement and abuse of power.
The Communist Party has acknowledged widespread corruption within its ranks. It has made a highly publicized effort to crack down on graft, pursuing charges against several lower level officials.
However, analysts point out that it is riskier for Beijing to go after senior officials, many of whom have reportedly used their leadership positions to amass huge amounts of wealth.