Social news website Digg.com is considering opening itself up further to allow other websites to copy its model, its co-founder has said.

In an interview with the Guardian, Digg chief executive Jay Adelson said the company was not looking to expand into more niche markets, but would prefer to "empower someone else" to do so.

Digg, which allows members to recommend news stories to the site's 21 million users, has become an online phenomenon since launching in 2004. Primarily known for technology news, it also helped launch spin-off video podcast Diggnation, which is watched by more than 300,000 people each week.

Adelson - who founded the website with former TV presenter Kevin Rose - told the Guardian that although Digg would expand in areas such as images, videos and business news, it was not interested in other areas such as politics or sport.

"There's value in vertical focus," he said. "But there may be a vertical which we choose not to go into: I would rather empower someone else to go down that route rather than do it myself."

Adelson said that Digg would not consider licensing its technology to other websites in order to let them create their own versions of the site, but that would make such systems "freely available".

"Sell the technology? No. We believe that if you love something, set it free," he said. "As far as enabling other third parties to do this sort of stuff, that's always been our intent. A very important point is that when we create tools to help people with that, there is no question that they will be freely available to the public."

He refused to comment further when pressed for more information, citing "confidential strategy".

Digg is seen as the poster child for a new generation of online news aggregators, which have drawn large audiences and admiring looks from traditional publishers. Several of the website's competitors have been bought in the past year, including Reddit.com - which was acquired by magazine and internet publisher Conde Nast - and Newsvine, a social news outlet recently purchased by MSNBC.com.

But Adelson - who recently signed a three-year deal which will see Microsoft provide exclusive advertising to the site - said that he was not interested in selling the company, which he believed deserved a valuation in excess of $100m.

"Digg, in and of itself, is an incredible opportunity alone," he said. "It should be driven as far as it can go that way. I've always said this… but if somebody can get us faster to where Kevin and I want to go, then rock n roll."

"But I have yet to meet someone who can do that."