In hidden corners across South Korea, tiny cameras are surreptitiously recording thousands of women when they are at their most vulnerable.

Women have come to fear that cameras could be anywhere: perched inside the toilet bowl of a public restroom, disguised as a smoke detector in a shop’s fitting room, even rolled into a plastic bag at the lip of a trash can.

In Seoul, the capital, the proliferation of such hidden cameras — and the images they record, which often end up on pornographic websites — has often been described by reporters as an epidemic.

The city announced a crackdown on Sunday, increasing the number of municipal employees assigned to search public bathrooms for hidden cameras to 8,000 in October from the 50 currently at work.