Kik social network indecent pictures claims investigated
Girls "as young as 12" have been targeted on a social network to send "indecent" images of themselves.
Parents have complained to police about approaches to children on the Canadian-owned messaging system Kik.
Sussex Police said youngsters were also being asked to meet those who contacted them.
Representatives of Kik, which is downloaded on to smartphones and used for social messaging, said the app had several key features to protect users.
'For own entertainment'
Police said they had received a number of reported incidents in West Sussex and they were being investigated as potential cases of child grooming.
A force spokesman said: "Girls as young as 12 have been persuaded to send indecent images of themselves after being befriended by people claiming to be older teenagers who have also encouraged the children to meet them in person.
"It is unclear how old those who have been approaching the children really are or whether they have asked for the images for their own entertainment or to pass among others.
"We are concerned they may pose a risk."
'Personal details protected'
In a statement, Kik said usernames identified users rather than telephone numbers, and personal information such as mobile phone numbers and email addresses were never shared.
"Only those people that users choose to share their username with are able to contact them on Kik, and all our users' personal information remains completely protected."
Kik said users were also able to block "any and all contact" with another user, without revealing to the other user that they had been blocked, which "instantly terminated any undesired contact from another user".
There was also an "ignore new user" feature, allowing users to hide messages they received from people they had never talked to before, and turn off notifications for those messages.
Kik said it had policies in place to respond "in the best way possible" when something was reported by a user or police
"Kik actively cooperates with law enforcement agencies all over the world, to ensure the safety of their users," it added.