At the end of December, a popular television series chronicling China's most famous empress suddenly went on a four-day hiatus.

When it returned on New Year's Day, the low-cut necklines and squeezed bosoms had vanished.

Instead, the screen was filled with close-up shots showing only the heads of the female characters in the period piece, which depicts the seventh-century Tang Dynasty, an era when a woman's beauty was defined partly by plumpness.

No one has claimed responsibility for the awkward cropping, but it is widely believed to be the work of the country's prudish censors.

The changes have drawn a wave of mockery from the public fed up with ham-handed censorship. Chinese have lit up social media with complaints and jokes, with some posting cropped photos of celebrities and drawings that add in the missing cleavages to show the absurdity of the cuts.

"It was not a public issue, but has become one after shameless officials wielded their powerful administrative powers," Ren Zhiqiang, a businessman who has been outspoken on social issues, wrote on his microblog.

"What people are concerned about is not cleavage, but that a bunch of cultural hooligans are in charge of making approvals."

Calls to the State Administration of Press, Publication, Radio, Film and Television were unanswered. The administration does not always issue its decrees publicly, issuing its orders instead directly to publishers and producers.

In recent years, the regulating agency has issued a series of edicts, saying TV programming should be wholesome and avoid smutty material that would corrupt social morals. It has banned plots that involve one-night stands, wife-swapping, female protagonists falling in love with more than one man and the use of sex in military espionage.

Bizarrely, authorities have also banned plots with time travel, a move they say is aimed at preserving historical integrity.

The risque necklines in The Empress Of China were the latest images to fall under the agency's cleaver.

The 80-episode series tells the story of Wu Zetian, who was a concubine to a Tang emperor but ascended to the apex of power and ruled officially under her self-proclaimed Zhou Dynasty. She is the only recorded woman to rule China in her own right and has been the subject of many television and film productions.

The empress was played by Fan Bingbing, a rising star who has appeared in the 2014 Hollywood blockbuster X-Men.

The series has lavish costumes with the low necklines believed to have been commonplace in the age of Wu, and all 80 episodes already had been produced when the changes were imposed after 17 episodes were aired.

In one survey by the industry research group Zero Power Intelligence, nearly 40 percent say the cuts were too prudish, though another quarter of the 13,768 respondents said the show was now appropriate for all ages.

The hubbub prompted at least two Communist Party-run newspapers this week to call for the introduction of ratings into Chinese television programmes and films.

"If there were ratings, then The Empress Of China would not need the redo," the Liaoning Daily wrote. "Now it has re-emerged with the bosoms covered up, yet the coy attitude has become an even bigger joke."

The party-run Henan Daily said that while the show was now suitable for all ages, "it has lost its edge".

Shi Shusi, a Beijing-based commentator, called it another example of the abuse of power.

"It's absurd that the authorities should make such a ruling when a few old cadres are upset with The Empress Of China,'" he said. "It's time we put powers in a cage so there will be sensible decision-making and management to prevent such a farce from happening again."