LONDON - The group known as Anonymous said Saturday it has hacked into some 70 mostly rural law enforcement websites in the United States, a data breach that one local police chief said had leaked information about an ongoing investigation.

The loose-knit international hacking collective posted a cache of data to the Web early Saturday, including emails stolen from officers, tips which appeared to come from members of the public, credit card numbers and other sensitive information.

Anonymous said it had stolen 10 gigabytes worth of data in all.

Tim Mayfield, a police chief in small-town Gassville, Arkansas, told The Associated Press that some of the material posted online -- pictures of teenage girls in their swimsuits -- related to an ongoing investigation, which he declined to discuss further.

Mayfield's comments were the first indication that the hack might be serious. Since news that some kind of an attack first filtered out earlier this week, various police officials dismissed it as nothing to worry about.

"We've not lost any information," was one typical response, given by McMinn County Sheriff Joe Guy to WDEF-TV in Tennessee on Tuesday.

But many of Guy's emails were among those leaked to the Web on Saturday, and others seen by The Associated Press carried sensitive information, including tips about suspected crimes, profiles of gang members, and security training.

The emails were mainly from sheriffs' offices in places such as Arkansas, Kansas, Louisiana, Missouri, and Mississippi. Most, if not all, of their websites were either unavailable or had been wiped clean of content.

Anonymous said in a statement that it was leaking "a massive amount of confidential information that is sure to (embarrass), discredit and incriminate police officers across the US." The group added that it hoped the disclosures would "demonstrate the inherently corrupt nature of law enforcement using their own words" and "disrupt and sabotage their ability to communicate and terrorize communities."

The group also posted five credit card numbers it said it used to make "involuntary donations." At least four of the names and other personal details published to the Internet appeared genuine, although those contacted by The Associated Press said they did not know whether their financial information had been compromised.

Many calls to various sheriffs' offices across the country went unanswered or weren't returned Saturday, but several others confirmed that a cyberattack had taken place.

In Arkansas, St. Francis County Sheriff Bobby May said his department and several others were targeted in retaliation for the arrest of hackers who had targeted Apple Computer Inc., among other companies.

"It's an international group who are hacking into law enforcement websites across the nation is my understanding," May told The Associated Press in a telephone interview. He said the FBI was investigating the attacks.

Although the hackers said the attack occurred days ago, many sheriffs seemed to first learn of its scope only when contacted by the AP.

"I had no idea that hackers had gotten into that email," said Mayfield, the police chief from Gassville.

Anonymous has increasingly been targeted by law enforcement in the United States and elsewhere following a string of high-profile data thefts and denial of service attacks -- operations which block websites by flooding them with traffic.

Last month the FBI and British and Dutch officials made 21 arrests, many of them related to the group's attacks on Internet payment provider PayPal Inc., which has been targeted over its refusal to process donations to WikiLeaks.

Earlier, 19-year-old Ryan Cleary was charged with attacks on the Britain's Serious Organized Crime Agency and various U.K. music sites. More recently, Jake Davis, alleged to be a spokesman for Anonymous known as "Topiary," was arrested on Britain's remote Shetland Islands by Scotland Yard's specialist e-crime unit.

Anonymous said the most recent attack was revenge.

"We are doing this in solidarity with Topiary and the Anonymous PayPal ... defendants as well as all other political prisoners who are facing the gun of the crooked court system," it said.

Many of the websites affected Saturday were registered to Brooks-Jeffrey Marketing Inc., a Mountain Home, Arkansas-based media services firm which provides support to law enforcement websites across the country. Anonymous said in its statement that it had pulled off its attack by compromising the group's server.

Brooks-Jeffrey Marketing did not immediately return calls and emails seeking comment.