A recent study by the University of Southern California has found that the increasing usage of the internet is worrying parents - one in five now believing their kids spend too much time on the Internet, and almost three quarters claiming grades at school are not improving.

|QUOTE|Forty-seven percent of the adults say they have withheld Internet use as a form of punishment.

Meanwhile, researchers have seen Internet use grow to 78 percent, from 67 percent, with access at home increasing to 68 percent, from 47 percent.

However, Jeffrey Cole, director of USC's Center where the study was conducted believes internet usage has now plateaued.

Americans 66 and over remain disconnected, with only 38 percent online, whilst all other age groups reaching 74 percent, with penetration hitting 99 percent for those 18 and under, the room for growth remains small.

On average, users are now spending 14 hours a week online, compared with 9.4 hours in 2000, with thirty-seven percent still have dialing-up for their Internet.

People may also be paying less attention to television commercials, Cole said; the study finding users using the program breaks to surf the web.

The study, which surveyed over 2,269 households over the two months February to April, has a margin of sampling error of plus or minus 3 percentage points.