SAN FRANCISCO - With backing from Al Gore, Current TV was launched four years ago as a mix of traditional journalism and viewer-produced content meant to create an open exchange with its audience.

But the plight of reporters Laura Ling and Euna Lee, imprisoned while on assignment in North Korea, has put the independent cable venture at the center of the news and challenged its culture of transparency.

While U.S. officials and family members have publicly called for the release of the women, Current TV has remained resolutely silent.

The media outlet has not commented or reported on the situation and has even taken the unusual step of deleting messages of support posted to its Web site.

Ling and Lee were accused of crossing from China into North Korea and sentenced by the top North Korean court last week to 12 years of hard labor for engaging in what the country called a politically fueled smear campaign.

Media observers said the cautious approach by Current TV could be justified when dealing with an unpredictable country such as North Korea. The cable journalists might not want to appear taking sides, so as not to jeopardize the jailed women.

Strategies of media companies differ when their journalists are endangered; some rally publicly in their defense, while others pursue back-channel negotiations, said Tala Dowlatshahi, New York director of the press-freedom group Reporters Without Borders.

Dowlatshahi warned against blaming the journalists or Current TV's "backpack journalism" approach, which outfits reporters with portable, easy-to-use technology that allows movement through dangerous territory.

Ling and Lee were seasoned reporters doing their jobs, she said.

"To say that this type of guerrilla journalism is putting journalists in more risk than traditional journalism is not the issue," Dowlatshahi said. "The issue is these women are not criminals, they're journalists, and they were not given proper legal treatment."

Current TV is backed by high-profile investors, including financier Richard Blum, Sun Microsystems cofounder Bill Joy, and former MTV and AOL executive Bob Pittman. It has 401 employees spread among its headquarters in San Francisco and offices in London, Los Angeles, and New York.

Billed as a mix of TV and the Internet, its content is intended to appeal to 18- to 34-year-olds. It had not turned a profit as of March 2008, according to documents filed with the Securities and Exchange Commission.

Current TV's approach is in many ways indicative of the direction media are going - covering international news using smaller, independent crews with new technology, said Bob Calo, a lecturer at the University of California, Berkeley's Graduate School of Journalism and former producer at ABC News and NBC News.

"There's an element of risk when you have a small crew and you're traveling low-profile, yes, but that's true for any journalist," Calo said. "It's typical of anyone embracing a digital model, an open kind of journalism."

The harsh sentences for Ling and Lee brought pleas for compassion from family and friends and calls for government talks by Secretary of State Hillary Rodham Clinton. The families have not publicly discussed Current TV's silence, but they have thanked Gore for his response.

"We talk to him regularly, and he is incredibly worried," Ling's sister, TV journalist Lisa Ling, said on ABC's Good Morning America. "He's doing everything he can to secure their release."

Former colleagues describe Laura Ling as dedicated to Current TV's mission of bringing untold stories from around the world to a young audience.

Ariana Reguzzoni was a producer in Current's "vanguard journalism" unit, where Ling is vice president. "She's really passionate about journalism and documentary," Reguzzoni said. "She traveled a lot and was willing to take risks for her job."