A recent film with a "remarkable" box office performance became the focus of a scandal involving the fixing of ticket sales figures.

Us and Them, directed by Taiwan singer, actress and writer Rene Liu, premiered on Saturday across the Chinese mainland. This nostalgic romance about Beijing white collar workers was expected to be hugely welcomed by fans before its release.

It earned 280 million yuan ($44.2 million) on its opening day. Even before its first screening, its pre-sale ticket revenue reached 122 million yuan, each setting a record for a romance film in Chinese cinemas.

However, now there are allegations the sales figures were manipulated.

Tickets worth at least 13 million yuan that were purchased through online film ticket sales platform Maoyan were reported to be refunded on Saturday night in thousands of cinemas nationwide.

Cinema managers were angered by the refunds, suspecting that most of the presale tickets were bought by production companies to create an illusion of its overwhelming popularity.

Maoyan also is an investor and distributor for Us and Them.

More than 40 percent of the screening plans in Chinese cinemas on Saturday were arranged for Us and Them. The number was even around 50 percent from Sunday to Tuesday.

"Cinemas always put profits as the priority," said Yang Jinsong, an independent film industry analyst and a freelancer with Hong Kong-based newspaper Takungpao.

"They were encouraged to arrange many resources for this film by the outstanding pre-sale performance.

"However, box office revenue of Us and Them began to fall on the second day after being released," he said. "It would be strange for a film, if it was really popular among fans."

Maoyan defended itself on Sunday, saying that "54 percent of refunds were to regular consumers" after its own investigation, and "part of the remaining 46 percent went to scalpers".

But the vague explanation has not deflected suspicion.

China Film Bureau, the country's watchdog of cinematic businesses, said on Monday that the refunding for the film is "abnormal" and further investigation is planned, according to a report by China Film News.

"Any behavior creating chaos in the film market and harming the collective interests of the industry is strictly forbidden," a statement released by the bureau said.

Director Liu's office said on Monday she would cooperate with producers and distributors of Us and Them to look with sincerity for the truth.

"It aims to bring the discussion of Liu's work to the film per se," a statement from her office said.

However, some experts said the incident could arouse the public's anger over the manipulation of box office sales, as has been the case in recent years.

For example, Ip Man 3, a 2016 martial arts film starring Hong Kong actor Donnie Yen and US boxer Mike Tyson, was heavily rebuked because the production team spent huge sums of money to buy its own tickets.

But what is suspected in Us and Them is different.

"Such refunding is unprecedented," Yang said. "It can easily gain the market with the lowest cost."

Nevertheless, he also said the incident will act as a lesson for Chinese cinema managers who overwhelmingly believe in online big data analysis.

"It will urge the industry to fix the leaks in the current system," he said.

China passed its national film industry promotion law in 2017, but more follow-up rules are still called for by professionals to better regulate the market.

Rao Shuguang, secretary-general of the China Film Association, said, China's film market has "overtaken the leading position" in some areas, and met some problems, which have never been encountered in Hollywood. For instance, over 80 percent of film tickets in China are now bought online.

"With the fast growth, this online industry is still reshuffling," Rao said. "Some operators will choose some inappropriate approaches to win more markets."

He also warned the danger of having a monopoly, which applies to the Maoyan case.

"Only when we have a more complete legal system can the Chinese film industry continue to boom in a healthy way," he said.

Xu Fan contributed to this story.