News Corp already charges for its Wall Street Journal website and claims it is the most successful paid news site on the internet. The Wall Street Journal is sold as digital content for Amazon.com's Kindle electronic readers, but News Corp says it is irked that Amazon doesn't share the identities of subscribers.

"Kindle treats them as their subscribers not as ours, and I think that will eventually cause a break between us," Murdoch said. However, News Corp is not likely to make an electronic reader that people could use to read digital newspapers because "we are not in the hardware business".

The strategy to extract fees from online readers is still lacking in many details, but News Corp executives have revealed they are in talks with Sony, which makes e-readers that compete with Kindle devices. Sony is on board with the notion that News Corp should know who is subscribing to digital versions of the Journal, according to Murdoch.

Most existing pay models at major news publications, News Corp's The Wall Street Journal and its rival Financial Times being the most prominent, allow casual users to read articles for free, but once value is established - that is, people start coming back for more - they ask for money. There's no direct value-addition, other than to make it possible to read content without jumping through hoops.

But charging readers for all content has not proved very successful so far, as people expect information on the net to be free. The New York Times hoisted a pay wall around its columnists, only to find that everyone stopped reading them. After their star journalists started to complain, the NYT abandoned the strategy.

The Wall Street Journal and Financial Times have actually had only limited success in charging for specialist financial news and comment. The proliferation of free online sources, aggregated by the search giant Google, has doomed to failure any attempt by others to extend such charges to general news content.