It had recommended that children have no screen time before the age of two.

But it now says children aged over 18 months can use video chat with family, and 18-month to five-year-olds can watch "high quality" programmes with parents.

However, it also says physical activity and face-to-face interaction should be prioritised.

It named programmes such as Sesame Street as examples of appropriate TV shows.

"Families should proactively think about their children's media use and talk with children about it, because too much media use can mean that children don't have enough time during the day to play, study, talk, or sleep," said Jenny Radesky, the lead author of the AAP report Media and Young Minds.

"What's most important is that parents be their child's 'media mentors'. That means teaching them how to use it as a tool to create, connect and learn."

The AAP has launched a tool to help families create a media plan to monitor screen use.

Two- to five-year-olds should be limited to one hour of screen time a day, and "media free times" should be created by carers, the guidelines add.

It also recommends installing "media free locations" in the home, such as bedrooms, for children including over-fives.

Dr Catherine Steiner-Adair, clinical psychologist and Harvard research associate, told the BBC that while she welcomed the new guidelines, they needed more explanation.

"There is a need for paediatricians to be very clear about what the content is, how much is to be co-viewed and what co-viewing is," she said.

"When you watch a video with a 24-month-old you want to be repeating the words over and over, pushing the pause button, the same way we do when we read to a child.

"Not two people sitting side-by-side watching in silence."
Measuring success

Dr Steiner-Adair also called for more research into the benefits of educational apps, describing them as an "unregulated" industry.

"I haven't seen who is developing the measures of learning for young children - what is actually going on?" she said.

"What we do know is the toddler brain lights up for learning language the most when they are being spoken to in real life, face-to-face, by a caring adult.

"I would like to see more of how they assess the actual learning that goes on between 18-24 months [via screens] and how they compare it to learning from being read to by an adult from a real book."