(AP) -- Major media executives are impressed with Twitter's growing popularity as a communications tool. They just can't figure out how the online messaging service is going to make money.

Twitter's business model was a hot topic Wednesday as an exclusive media summit began at a posh resort in the Idaho mountains.

The skepticism about Twitter's potential surfaced during a panel focusing on how to capitalize on digital media. That's according to panel moderator Ken Auletta of The New Yorker magazine. Other reporters were locked out.

Two of the panel participants, InterActiveCorp CEO Barry Diller and cable TV mogul John Malone, amplified on their Twitter doubts in separate interviews.

CEO Evan Williams declined an interview request as he left the digital media session.

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