Police in South Korea have arrested four people on suspicion of secretly filming about 1,600 guests in hotel rooms and posting or streaming the footage on the internet.
The Korean National Police Agency said mini-spy cameras were set up in TV set-top boxes, hair dryers and electrical outlets in 42 rooms in 30 hotels throughout South Korea.
A police statement accused the men of earning about 7 million won (£4,700) by posting or livestreaming the footage on an overseas-based internet site they opened late last year.
If convicted, the two main culprits could each face up to seven years in prison, according to police.
One of the main suspects allegedly installed the cameras after entering the hotels as a guest. The other was accused of being responsible for launching and managing the now-closed website.
The other two were allegedly involved in buying the spy cameras or funding the internet site's operation, according to police.
Officers said they are the first South Korean arrests for livestreaming the private lives of hotel guests on an overseas-based website.
The illicit distribution of video taken by hidden cameras is a serious social problem in South Korea.
Thousands of women rallied in Seoul several times last year, demanding stronger government measures.
In a separate case, a Seoul district court was reviewing whether to issue an arrest warrant for a pop singer on allegations that he secretly filmed himself having sex with women and then shared the videos with friends in mobile group chats.