WASHINGTON (AP) — Federal regulators unanimously approved rules Thursday requiring television stations that air more than one digital channel to show additional children’s programming — in some cases up to 18 hours of kids’ shows a week.

Currently, the Federal Communications Commission requires a broadcaster to air three hours of children’s shows each week on its main analog channel.

Under the new rules, a broadcaster that multicasts a digital signal to air two or more channels will be obligated to show three extra hours of kids’ TV a week for each 24-hour multicast channel. With digital signals, a broadcaster could have as many as six channels.

“At a time where broadcasters using the public airwaves may now be able to increase their programming by as much as six times the content they used to, so too should their obligations to serve our nation’s youth increase,” said FCC Chairman Michael Powell.

Children’s advocacy groups praised the decision, saying parents and their children will benefit from more educational programming.

“We know it’s good for kids. Research shows it’s good for kids, and we wanted to make sure kids have access to a sufficient amount of it,” said Patti Miller, director of the kids and media program for Children Now, a children’s advocacy group, after the commission’s vote.

The new rules also require both analog and digital stations to carry the electronic marker “E/I” — for educational and informational programming — somewhere on the screen throughout the entire show. The idea is to better help parents identify children’s programs.

Some children’s groups had pressed for a ban on interactive ads, which would allow kids watching a TV show to touch the screen or click on a character and be taken directly to an Internet site for the program. But the agency concluded that such a move would be premature, since “this technology is not yet in use in children’s programming.”

Broadcasters that multicast only part time on a channel won’t have to air as many hours of kids’ TV as a 24-hour channel would.

The broadcasters also will have some flexibility in satisfying the rules. They could opt to put the additional children’s shows on the multicast station or add them to the three hours already required on the main station.