NEW YORK?The biggest challenge to Cable News Network is not other 24-hour television news stations but social networks like Facebook and Twitter, the president of CNN US said Wednesday.

"The competition I'm really afraid of are social networking sites," Jon Klein said at the Bloomberg BusinessWeek 2010 Media Summit here. "That's an alternative that threatens to pull people away from us.

"The people you're friends with on Facebook or the people you follow on Twitter are trusted sources of information," Klein said. "You click on links they send to you and you trust them.

"Well, we want to be the most trusted name in news," he said. "We don't want the 1,000 people you follow in Twitter to be the most trusted sources for you.

"That's a challenge and we have to rise to that challenge," Klein said.

"So I'm far more worried about the 500 million people on Facebook than I am about two million people watching Fox," the News Corp-owned station which is CNN's major competitor in the cable news arena, Klein said.

The CNN executive said his network's "mission" is to drive social network and other Web users to "link back to something on CNN."

Besides expanding its footprint on the Internet with news and video, CNN is looking at mobile devices, Klein said.

"Online is a big growth area for us, mobile has enormous growth potential and domestic US cable is actually a growth area," he said. "There's a lot of room to grow.

"We're in a lot of places and I think that's the model that can be very successful for us," Klein said. "Everyone in the media business is actively looking for multiple revenue streams, that's no secret."

Klein, a longtime producer at broadcast network CBS who took over as head of CNN's US operations in 2004, also said that with the explosion of news outlets and the Internet just being at the scene of a news event was no longer enough.

"Simply getting there used to be a big achievement," he said. "Nowadays, you've got to provide more than just being there.

"Offering the depth and analysis is harder," he said. "It takes more brainpower, it takes more work, it takes more thought, it takes more creativity.

"People are pretty up to speed on what happened today," he said. "You've got to give them more insight about what's going on. That is where we are going to try to continue to make a difference."