NEW YORK - One in every 25 teens reported an "irresistible urge" to be on the Internet, tension when they weren't online, or said they had tried to quit or cut down on Internet time, according to a US study.

In addition, the study of more than 3,500 high school students in the state of Connecticut found that those students with "problematic Internet use" were more likely than their peers to be depressed and aggressive, and to use drugs.

But study leader Timothy Liu, at Yale University, and his colleagues said they couldn't prove a "cause and effect" link between the Internet habits, depression and drug use.