Charging online readers will give The New York Times a critical second revenue stream but the print newspaper will be important for "many years to come", publisher Arthur Sulzberger says.

Sulzberger, speaking at the Bloomberg Businessweek 2010 Media Summit in New York, also said he had no intention of selling the newspaper, which has been in his family for generations.

The Times Co announced in January that it would begin charging readers of NYTimes.com in early 2011, using a "metered model" that will offer users free access to a set number of articles before they will be asked to pay.

"The model we are going to be putting into place in early 2011 will allow us to continue to be part of the social media ecosystem, as well as bring us that critical second revenue stream that ... is going to be critical to supporting the journalism that we do," Sulzberger said.

"We believe that going to a metered model is absolutely the right thing today," Sulzberger said. "But will it be the best thing 10 years from now? I don't know."

Times Co president and chief executive Janet Robinson said "there is an opportunity, I think, for us to gain a great deal of revenue from this paid model going forward."

Sulzberger said that "for those New York Times customers who want print, it is not as though print is going away".

"It's a critical part of today, it will be a critical part I think for many years to come," he said.

"The iPad is also going to be a critical part just the way the Kindle's a critical part.

"At the end of the day we can't define ourselves by our method of distribution," Sulzberger said. "What we care about at the end of day is our journalism, our quality journalism."

Sulzberger also said that he was "delighted" to have Mexican billionaire Carlos Slim, who was named the world's richest man by Forbes magazine on Wednesday, as a major investor in the Times.

Slim extended a $US250 million ($A273.19 million) loan to the Times last year.

"He's invested because he believes in our mission, and he believes in the quality of what we do, and that his shares will, in fact, rise," Sulzberger said.

"Shareholders who don't share the vision of where the New York Times Company is going or how we're operating are going to bail," he said. "They're going to sell.

"Because, if they don't buy into what we're doing, then that's not a good investment for them," the Times publisher said.