It might usually be a bad idea for a reporter to become part of the story, but Google News is making headlines amid suggestions the service is already influencing the news agenda.

Since 2001, the site has sought to offer a one-stop window into world events. It gathers and sorts millions of stories a month from around 4,500 news sources and allows users to click through to read them on the sites they come from.

"Where traditionally you had one source, one paper, with multiple stories, now you have one story and several perspectives," Debbie Jaffe, Google's senior marketing manager for consumer products, told Times Online.

People seem to like having their news sorted in this way, but there are suggestions that the power of Google News is distorting journalists' news judgment. Joel Achenbach, a Washington Post journalist, recently called Google "the tail that wags the blog," arguing that some online writers now work "as though their primary goal is to rise in the Google search results".

On the online diary he writes for the Post, Mr Achenbach said: "The more you mention people like Brad Pitt and Angelina Jolie, the more readers you will have ... and the more you will rise in Google's estimation."

This estimation is important because, as a window to potentially massive audiences, Google can make a huge difference to a site’s commercial fortunes. It has more than 6 million users a month and can, in the words of one national newspaper’s web analyst, "transform an ordinary traffic day into a very good traffic day" by picking up just one story and channelling readers towards it. Such is the company's power, editors are prepared to sign non-disclosure agreements - documents that go against the basic principles of their trade - to catch a glimpse of what Google might have in store for their industry.

Google recognises the influence it holds in the daily battle for readers and advertising revenues. It portrays itself as "an honest broker" that merely mirrors the news agenda as it appears on the web and says it is a servant of both its users and the multi-billion dollar global news industry.

"We like sending users off our site as quickly as possible," Nathan Stoll, Google News product manager, said. "We supply news sites with readers – with traffic.

"And there’s a larger argument here. Google News creates consumers for news organisations. People become news enthusiasts through the site and by providing multiple perspectives on events we encourage people to dig into topics and to follow them more closely. In that way, we have a complementary relationship with the newspapers."

Google’s critics argue that with its power should come responsibility and a commitment to transparency. At the World Editors' Forum in Seoul earlier this year, there was a vigorous disagreement between Krishna Bharat, the creator of Google News, and American and Japanese speakers over Google's reluctance to reveal exactly what sources it uses and how it adds or subtracts from the list.

However, Mr Stoll argues that the technology that takes the place of the news desk and backbench – the departments of a newspaper that decide what will be covered and where it will appear – absolves Google from conventional notions of editorial accountability.

"We’re just computer scientists … we’re reliant on third-party editorial sources," he said, suggesting there is no great mystery over how Google News chooses and orders its stories.

"The process can be split into four technical processes. First we crawl and index all the news sites we have listed. Second we cluster stories into topics. Third, those clusters are classified. And in the final step, an algorithm is employed which tries to reflect a traditional editorial process."

Echoing the early days of Kellogg’s cereal, Google looks to offer Google News as a product "untouched by human hand". Mr Stoll argues this is possible because of the way an event’s editorial weight is measurable online - partly through the weight of copy written on it.

"A small event has a small impact on the web, a big event makes a big impact. That reflects editorial judgment, which is something we are able to quantitively evaluate," he said.

"Other factors, such as who is publishing a certain story and the question of whether original material is being crawled are also taken into account."

However, people do play a part in the process. News sources are tagged – "by hand" – to avoid, say, spoof articles on a satirical site such as The Onion appearing among a list of straight news stories.

Likewise, a computer algorithm cannot be left to weed out defamatory or offensive content. "It’s absolutely the case that we would remove anything that we were notified promoted hate or violence. That’s a long-standing position of ours," said Mr Stoll.

And bias can creep in. One of the anecdotes from the early days of Google News involves an English programmer whose choice of sites for Google's "bots" - its automatic computer robots which trawl the web - to crawl led to cricket dominating the sports section, much to the bemusement of his American colleagues.

Too much cricket and not enough baseball is, for most people, hardly big news. But reports emerged earlier this year that Google is working on a product that would order stories according to the trustworthiness of their publishers.

Would Google be able to invoke the technology – "untouched by human hand" – argument if it were to take the line, say, that the BBC was less trustworthy than the New York Times? And what might be the reaction from the Telegraph if the Guardian was judged a more reliable organ?

"We’re absolutely not going to talk about things relating to patents," Ms Jaffe said when the subject was raised.

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