Figure equals average of 72 strangers per child.
According to data found in a new research report, the average 12 to 15-year-old has never met one in four of their 'friends' on social networking networks such as Facebook.
Telecoms and media regulator Ofcom's annual Children and Parents: Media Use and Attitudes Report found that 12 to to 15-year-olds spend an average of 17 hours per week on the internet, as well as the possibility of over a third of three and four-year-olds using the internet for TV and games.
More than 40 percent of five to 15-year-olds who utilize internet access boast a social networking profile, which has risen to 80 percent among 12 to 15-year-olds.
The older age group has an average of 286 online friends, with 93 percent of them stating they are confident they acknowledge online safety. However, the report suggested that 12 to 15-year-old's have not met an average of 25 percent of the friends on sites including Facebook, which equals an average of 72 strangers per child.
"Children are not just using more media, they are also adopting some forms [of it] at a very young age," said Claudio Pollack, consumer group director at Ofcom.
The regulator also said it has seen a 50 percent rise in smartphone ownership among the latter age group year on year. Almost two thirds of 12 to 15-year-olds now own a smartphone.