A new wave of “silent camera” applications – some specifically designed for voyeurism – has been blamed for a huge rise in illicit photography in Japan.

Most smartphone cameras have a built-in shutter noise to prevent the camera being used to take pictures without people’s consent.

There were 1,741 incidents last year in Japan, according to a report in Mercury News, with an increase of 60% on the figure five years ago.

The problem is blamed on the rise in “silent camera” apps – including ones which deliberately conceal what the user is doing by putting an innocent-looking email or text message on screen while he or she photographs.

Most smartphone cameras have a built-in shutter noise to prevent the camera being used to take pictures without people's consent

There are dozens of silent camera applications already available on Android Market and iTunes store – and on Android particularly, and several that appear to market themselves as being for stealthy photography.

Mercury News report says: “The latest applications include <<upgraded versions>> that enable people to silently take photos while an email or website is displayed on the phone’s screen to provide cover for the surreptitious picture-taking.”

Japanese academics have called for regulation of silent photography applications – saying that they are being used for crimes.

With Google’s “anything goes” policy on Android, where applications are not vetted before publication on Market, and users can also download apps from elsewhere on the web, it will be very difficult to police.

Most smartphones also include a way of disabling the noise of camera applications even in the built-in apps.