News Corp is not interested in buying Twitter and will not sell its struggling social network MySpace, chief executive Rupert Murdoch said on Wednesday as the second day of the Allen & Co.'s Sun Valley media and technology conference got under way.

According to Reuters, Murdoch said Twitter would be a tough investment to justify because it has not yet come up with a sustainable way to make money. "Be careful of investing here," he said of Twitter.

Asked about selling MySpace, he said, "Hell no."

There's much speculation at the 27th conference about which company might want to buy Twitter. Older media conglomerates are always on the outlook to buy hot Internet start-ups, and Evan Williams, Twitter co-founder, is considered one of the darlings of this year's conference.