More than half a million Germans are addicted to the Internet including a full five percent of mid-teen girls, the government said Monday following an unprecedented study. Some 560,000 or around one percent of the population between the ages of 14 and 64 cannot control their use of the web, with the youngest users the most vulnerable, said the government's top addiction specialist, Mechthild Dyckmans. The study, conducted by two eastern German universities, defined web addiction as excessive use, dependence on the web to escape from reality and indifference to serious consequences from the amount of time spent online. "These are often people who have not found much recognition in real life and who have difficulty making friends," Dyckmans said of the addicts. "Those are the people who feel more comfortable looking for friends online." Dyckmans said about 2.5 million Germans between the ages of 14 and 64, or 4.6 percent, were "problematic Internet users" with some difficulty limiting their surfing. Five percent of girls of that age -- the most affected group -- were considered Internet-addicted, in large part due to their devotion to online social networks such as Facebook. Boys the same age were slightly less affected with only three percent hooked on the web. Their biggest temptation was online games. Dyckmans said the government now aimed to develop a standardised diagnosis to find better treatment options. The study was based on telephone interviews with 15,023 Germans.