Four of the five missing Hong Kong booksellers have appeared on Chinese TV, saying they have been detained for "illegal book trading" on the mainland.
The men said they had sold 4,000 "unauthorised" books to 380 customers in mainland China, Phoenix TV reported.
The five men, who disappeared late last year, worked at a publishing house that sold books critical of China's leaders.
Some people in Hong Kong believe they were detained by China because of a book about President Xi Jinping.
Four of the men from Mighty Current publishing house, Gui Minhai, Lui Bo, Lam Wingkei and Cheung Jiping, gave details of their alleged offences during their appearance on Phoenix TV (in Chinese) on Sunday.
Public confessions have long been a part of China's criminal law, but experts say many confessions are forced.
Mr Gui, a Swedish national, said he had concealed the books in bags to "evade" customs and was identified by the other detainees as having been in charge of the operation.
Mr Lui said: "I have deeply reflected on what I have done and very much regret the illegal book trading I have carried out with Gui Minhai."
Meanwhile, Mr Lam said the books' content had been "fabricated".
"They were downloaded from the Internet, and were pieced together from magazines. They have generated lots of rumours in society and brought a bad influence."
Mr Lam, Mr Lui and Mr Cheung had shown a "good attitude" by confessing and might be allowed to return to Hong Kong this week while they await trial, Phoenix TV said, citing police sources.
However, Mr Gui was expected to remain in China. He had appeared on Chinese TV in January saying he voluntarily handed himself over to the authorities over a fatal drink-driving incident more than a decade ago.
The Swedish foreign ministry said an envoy had visited Mr Gui and said his condition was "very good".
Lee Bo not shown
The fifth detainee, British national Lee Bo, who disappeared from Hong Kong in December, was not shown.
The Phoenix TV report said Mr Bo had voluntarily handed himself over to the mainland authorities to assist in the investigation.
However, his travel document was found in Hong Kong after his disappearance and the Hong Kong authorities said they had no record of his having crossed into the mainland.
The UK has said Mr Bo was probably "involuntarily removed" to China, calling it a "serious breach" of the handover treaty that undermined the principle of "One Country, Two Systems".
Under Hong Kong law, Chinese police do not have jurisdiction in the territory.
The case has sparked international concern that China could be attempting to rein in freedom of expression in Hong Kong.
However, China's foreign ministry has said its officials would not behave illegally, and urged other countries not to meddle in its affairs.
Mighty Current publishing house disappearances
1. Lui Bo, General Manager, goes missing in Shenzhen, 15 October
2. Cheung Jiping, business manager, 32, goes missing in Dongguan, 15 October
3. Gui Minhai, co-owner, 51, goes missing in Thailand, 17 October
4. Lam Wingkei, manager, 60, last seen in Hong Kong, 23 October
5. Lee Bo, shareholder, 65, goes missing in Hong Kong, 30 December