ZHENGZHOU - Police in Luoyang, Henan province, have apologized over a case in which six women are alleged to have been held as sex slaves. Two of them were murdered.



Guo Congbin, director of the public security bureau of Luoyang, told a news conference that four district police officials had been suspended for negligence.



An application to charge the suspect, Li Hao, 30, a former firefighter who worked later in the local technological supervision bureau, is before the public prosecutor.



Police allege Li spent more than a year building a dungeon under a basement he had bought in an apartment building before kidnapping the six women, aged 16 to 24, at different times and forcing them to perform erotic shows on the Internet.



Li had come up with the idea after realizing how lucrative "videos of such performances" could be, police said.



Li also allegedly took the women out to prostitute themselves at night whenever he needed money, and killed two who had disobeyed before burying their bodies in shallow graves in the dungeon.



A woman escaped during one such outing and led police to Li and the basement.



Earlier reports said the four rescued women had been detained because they might have helped Li kill the other two women. Police confirmed the women are being held, but would not say why.



Investigations are continuing, said the director of Luoyang public security bureau, Guo Congbin.



He apologized on Saturday to local residents, saying police "should have detected the crime earlier had they done their work more meticulously".



Guo acknowledged that there had been "insufficient communication" with media about the case, but stressed this was because it needed to be investigated further. Regulations had been followed, he said.



Li was detained on Sept 3, but the case was only made public after Southern Metropolis News in Guangzhou reported it on Thursday.



"We failed to let the public know in time what they should know about the case," Guo said.



Media reports had accused local authorities of trying to stop the kidnappings and murders being made public.



On Friday police said that updates on the case would be posted on their Sina Weibo microblog.



Guo promised to reinforce public security so similar crimes could not be committed, starting with a "crackdown" in the city.



Neighbors of Li said they had had no inkling of the crimes until seeing about them in the media.



Police said Li had managed to avoid detection by building the dungeon and kidnapping the women at night.