Kensington Palace has accused paparazzi photographers of harassing Prince George and Princess Charlotte, accusing them of going to "extreme lengths" to get pictures and urging the media not to use the images.
In a letter issued today, the palace said photographers were using surveillance techniques to try to get pictures of the young royals.
On one occasion last week a photographer set up a 'hide' in his car as he staked out a children's play area.
Hiding in sand dunes on a rural beach
Other incidents have included: photographers pursuing cars leaving family homes; using other children to draw Prince George into view in playgrounds; hiding on private property in fields and woodland around the Duke and Duchess's home in Norfolk; and hiding in sand dunes on a rural beach to take photos of Prince George playing with his grandmother
In the letter, Kensington Palace Communications Secretary Jason Knauf said: "It is of course upsetting that such tactics - reminiscent as they are of past surveillance by groups intent on doing more than capturing images - are being deployed to profit from the image of a two-year-old boy.
"In a heightened security environment such tactics are a risk to all involved.
"The worry is that it will not always be possible to quickly distinguish between someone taking photos and someone intending to do more immediate harm."