MEXICO CITY (AP) — Police in Mexico City have issued a warning about a new type of "ransom ware" virus that can take over computers' cameras and make the user think they are under surveillance.

The Mexico City police department's cyber-crime unit says the virus infects computers, generally after they view or download sexually explicit material.

Police say a message appears on the screen from a "supposed police agency" saying the user must pay a fine via electronic transfer.

Such viruses have circulated widely in recent years, but the latest version sometimes takes control of the computer's camera and shows footage in a pane on the screen, "making the user believe he is under surveillance."

Police urged users in a statement not to pay the supposed "fines."