No hidden cameras have been found in women's toilets at a busy shopping mall in downtown Xuhui District, Shanghai, police said yesterday.
This follows online claims that secret footage had been taken at Metro City in the Xujiahui area and used in Japanese adult films.
Police and security guards checked all 20 toilets at the mall yesterday and discovered nothing, officers said. They said investigations were continuing.
Concerns were raised in an online post, titled "Caution Girls" late on Saturday, which claimed that hidden cameras had been used to secretly record women in toilet booths.
Women featured in clips spoke Shanghainese, claimed the poster.
The footage was sold in Japan, said the post, and featured in adult movies commercially available there since April 30.
In total, there were 20 clips, according to the poster, who uploaded some pictures said to have been recorded at Metro City.
These showed women, apparently unaware they were being filmed, recorded by cameras positioned above and below.
Police began an investigation after the post spread quickly online, with many web users expressing their anger and concerns about privacy.
Officers did not disclose whether they had traced the source of the online post.