French bloggers have dubbed it "la gaffe d'AOL". The internet business had meant to release samples of search engine queries to the online "research community" - to give a select group of technology boffins a taste of the character of online America.

Instead, because of what AOL called an unmitigated "screw-up", it released details of 20 million private search queries from 658,000 of its users to the online public at large.

The collection, quickly disseminated across the web by bloggers, provides a disturbingly intimate picture of some of AOL's user base.

Alongside searches for Angelina Jolie and Britney Spears, darker queries typed into the AOL search engine included: "how to tell your family you're a victim of incest" and "how to kill your wife".

Potentially incriminating entries included: "cocaine in urine".

Websites quickly assembled compendiums of the grimmest, bringing together questions on "how to secretly poison your ex"; "ways to kill yourself"; "how to starve yourself" and "my boyfriend threatened me with a knife and went to jail now im worried he'll hurt me when he gets out".

AOL, which is owned by media giant Time Warner and Google, took the data down the instant the mistake was realised and issued an apology, but by then the information had been duplicated on sites across the internet.

Indeed, one blogger has already built a customised interface that lets curious surfers gawk at the online habits of AOL users without having to trawl through the 20 million queries.

Meanwhile, although the people who entered the search terms were identified only by random seven-digit numbers, bloggers quickly pointed out that a little online detective work - using a search engine such as AOL's own - could uncover their identities.

TechCrunch, a blog, said: "The utter stupidity of this is staggering ... The data includes personal names, addresses, social security numbers and everything else someone might type into a search box."

It added: "The most serious problem is the fact that many people often search on their own name ... Combine these ego searches with porn queries and you have a serious embarrassment. Combine them with "buy ecstasy" and you have evidence of a crime. Combine it with an address, social security number, etc., and you have an identity theft waiting to happen. The possibilities are endless."

The story appears to have been broken when Greg Linden, the software expert and blogger who created the "recommendation engine" used by Amazon.com, the online retailer, pointed out how valuable the data could be for software developers working on search problems.

That post was picked up by another blogger, Adam D'Angelo, who took an altogether dimmer view.

"This was not a leak - it was intentional," he said.

"In their desperation to gain recognition from the research community, AOL decided they would compromise their integrity to provide a data set that might become often-cited in research papers: 'Please reference the following publication when using this collection...' is the message before the download."

The timing could hardy have been worse. AOL last week announced a change in strategy under which it will give away web services such as e-mail free (before users had to pay subscription fees) in an effort to increase traffic to its sites and hence advertising revenues.

But bloggers queried if companies such as AOL can ever be trusted with private information.

"When those who want ISPs/telecoms to retain data, they always try and placate the masses by saying that it will be adequately protected," said the PlanetPotatoe blog

"It never is and is invariably abused by whomever has least interest or knowledge in protecting the data."

The lantinioustesh site said: "The sheer amount of data they collected is kind of disturbing. A user ID#, the keywords, the time, and the selected search result. That's some pretty detailed stuff for 'anonymous' search data."

AOL now faces a battle to rebuild its reputation. But support did come from one unexpected quarter - arch rival Microsoft, which has its own research facility that looks at seach queries. Microsoft is not alone in thinking that query data is an invaluable resource that must be examined outside of the companies that gather it to improve search technologies.

"AOL Research — thanks for pushing on this," Dr Erik W. Selberg, who heads the algorithmic Web search relevance group at Microsoft, said.

"Yeah, you’re getting a bit roasted right now, but we all need people like you guys to push to get things done. Sometimes mistakes will be made, but the alternative is that no one ever takes a risk, and progress just grinds to a halt."

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