Chinese officials reportedly said that four of the five missing Hong Kong booksellers had been detained because they illegally traded books on the mainland. The men were also seen on China's television confirming the accusation late Sunday.

The men were associated with the publishing house, Mighty Current, and its retail outlet, Causeway Bay Bookshop, and have been missing for months, sparking speculations that China had detained them in an effort to curb civil rights in Hong Kong.

A Chinese media outlet first reported that Gui Minhai, one of the missing men, had confessed to selling over 4,000 books on the mainland by mail, despite knowing that they had not been approved by the Chinese government, according to the Associated Press (AP). Gui, who holds a Swedish citizenship, has been missing since October, until resurfacing in January on Chinese media. He made a tearful appearance on the network last month saying that he had surrendered for violating his probation that stemmed from a drunken driving case 12 years ago.

According to a report by the South China Morning Post (SCMP), which cited Shanghai-based website, Gui allegedly ordered his associates to mail the books to about 380 buyers across 28 cities and provinces on the mainland. The other three men were identified as Lui Por, Cheung Chi Ping and Lam Wing Kee. The report also hinted that the four men could be allowed to go home in a few days because of their “good attitude.”

“I have deeply reflected on what I have done and very much regret the illegal book trading I have carried out with Gui Minhai,” Lui said in the address on Phoenix Television, according to Reuters. Lui also said: “What I have done was under the influence of Gui. It was Gui dragging me down the path of crime,” according to SCMP.

While Gui went missing from Pattaya, Thailand, the others went missing from mainland China. In the address, Gui said that he had altered and obscured the covers of the books in order to avoid security checks, Reuters reported. The group of men had also allegedly opened a bank account in China to make payments.

“I know that Gui Minhai's books are fabricated. They were downloaded from the Internet, and were pieced together from magazines,” Lam said, according to Reuters, adding: “They have generated lots of rumors in society and brought a bad influence ... I deeply acknowledge my mistakes and am willing to be penalized.”

The fifth person, not seen in the address, was Lee Bo, a British citizen who has been missing since Dec. 30, 2015, triggering speculations about whether he was abducted by Chinese officials working in Hong Kong. If this turns out to be true, it would stand as a violation of the "one country, two systems" principle that Beijing agreed to put in place when it took control of Hong Kong from Britain in 1997.

Several countries have expressed concern over the case, according to the AP, and the European Parliament has asked that the five men be released immediately. Mighty Current’s books usually center on political scandals surrounding China’s communist leaders and are popular with Chinese visitors to Hong Kong.