Britain's Royal Family has accused photographers of harassing Prince George and Princess Charlotte, and going to "extreme lengths" to get pictures.
In an open letter, Kensington Palace said incidents include paparazzi pursuing cars leaving family homes, steady surveillance of some family homes, and following household staff around.
It said such tactics were upsetting for the family, and the Duke and Duchess want their children "to be free to play in public with other children without being photographed".
The Palace said other incidents included paparazzi hiding in sand dunes on a beach to capture the two-year-old Prince playing.
In the past week, one photographer set up a "hide" in a car as he staked out a children's play area.
The Palace said a small number of magazines, mostly in Germany, France, Australia, New Zealand and America, have published photos of the Queen's great-grandson taken in what it calls "unacceptable circumstances", and the worry was that it wouldn't always be possible to distinguish between someone taking photos, and someone intending to do harm.
British journalist and royal watcher Roya Nikkhah told CNN photographers have also used other children to try to lure George into camera shot.
"Photographers, paparazzi have used other children, either their own children or friends' children, to try and engage with Prince George, to try and play with him and move him into position," Ms Nikkhah said.
"And if you think about that, this is a two-year-old boy, that is incredibly sinister."
And the Royal Family urged the world's media to stop buying pictures of Prince George from paparazzi.
Yet undercover paparazzi continue to pursue their children, selling images of Prince George to international publications.— Kensington Palace (@KensingtonRoyal) August 14, 2015
Officials said among the photographers who have crossed the line was one found aiming his lens through a spyhole in the boot of his car.
Ms Nikkhah said that around the world, if George was on the cover of a magazine, sales rocketed.
London's Metropoloitan Police, which is responsible for the safety for the Royals, also warned that photographers ran the risk of being shot if they try to get too close to the Prince and Princess.