Screen addiction is causing toddlers to lose delicate coordination skills such as those needed to tie their shoelaces, research suggests.
A study of 2,400 children found that more screen time was linked to lower scores in "milestone" tests of coordination, as well as communication, problem-solving and social skills.
The amount of time two and 3-year-olds devoted to screen-gazing had a negative effect on their performance at three and five.
Scientists behind the study said that staring at screens may be causing children to miss out on the chance to practise physical and intellectual skills.
By the time they start school, a quarter of children show some degree of deficient or delayed development in language, communication, motor skills and "socio-emotional health", the researchers said.