The more television 4-year-old children watch the more likely they are to become bullies later on in school, a U.S. study said.

At the same time, children whose parents read to them, take them on outings and just generally pay attention to them are less likely to become bullies, said the report from the University of Washington.

Bullying can now be added "to the list of potential negative consequences of excessive television viewing along with obesity, inattention and other types of aggression," said Frederick Zimmerman who led the research.

"Our findings suggest some steps that can be taken with children to potentially help prevent bullying. Maximizing cognitive stimulation and limiting television watching in the early years of development might reduce children's subsequent risk of becoming bullies," he added.

Previous research had indicated that emotional support from parents helps young children develop empathy, self-regulation and social skills, making them less likely to be bullies, said the report published in the April issue of the Archives of Pediatrics and Adolescent Medicine.

Researchers have also found that early gaps in learning and understanding may make children less competent in dealing with their peers and that violence on television leads to aggressive behavior, it added.

The Washington study reached its conclusions by looking at data from a study of 1,266 four-year-olds whose bullying -- based on assessments from their mothers -- was tracked at ages 6 through 11. Overall, about 13 percent the children turned out to be bullies.

The study also took into account the stimulation the children received as measured by outings, reading, playing and what role the parents played in teaching the children.

Whether the child ate meals with both parents, whether parents talked to the child while working were also measured, along with the average number of hours of television viewed.