Chinese state broadcaster CCTV claimed on Tuesday its Twitter account had been "targeted", after a tweet appeared saying a former security chief was being probed for graft.
On Monday, CCTV's official Twitter feed briefly stated: "President Xi Jinping has set up a special unit to investigate corruption allegations against the retired leader Zhou Yongkang."
If true, the news would have been confirmation of a major factional fight within China's ruling Communist party, and a radical departure from the principle of recent decades that its highest leaders remain untouchable, even after stepping down.
But the tweet, which was soon deleted, appeared to be an uncredited repetition of a similar story published earlier that day by the Hong Kong-based South China Morning Post newspaper, which attributed it to unnamed sources.
In a statement posted to its Twitter feed Tuesday, CCTV said: "The CCTVNEWS Twitter account was targeted on Oct 21st and used illegally to post incorrect information copied from other sources. The unauthorised information was deleted."
The comment raised scepticism online. "Was the tweet the mistake of an intern?" asked Jeremy Goldkorn, a media and Internet commentator in China.
Twitter itself is blocked in the country, where the government maintains a vast network of controls on the Internet known as the Great Firewall of China, a fact not lost on some posters.
"What are CCTV doing with a twitter account in the 1st place?" asked one.