US authorities were investigating Tuesday after hackers posted personal financial data belonging to First Lady Michelle Obama, the head of the FBI and several A-list celebrities online.

Hackers using a Russian web address published the credit reports and social security numbers for Obama, Federal Bureau of Investigation Director Robert Mueller, US Attorney General Eric Holder, and Los Angeles Police Chief Charles Beck.They also posted social security numbers and other personal information relating to Vice President Joe Biden and former first lady and secretary of state Hillary Clinton.

Entertainment stars Beyonce and husband Jay-Z, Paris Hilton, Kim Kardashian and Britney Spears also saw details leaked, as did tycoon Donald Trump, former Alaska governor Sarah Palin and bodybuilder-turned-actor and former California governor Arnold Schwarzenegger.

The three leading personal credit-rating agencies acknowledged the files were accessed illegally, but said it was done through other firms by someone using the personal data of the victims, and not by hacking their own computers.

"This looks to be an isolated situation in which criminals accessed personal credential information through various outside sources, which provided them with sufficient information to illegally access a limited number of individual reports from some US credit reporting agencies," said Experian."Upon learning of the situation, we took immediate action to freeze the credit files of those victimized by this malicious attack in an effort to minimize impact to those individuals."

Transunion, the source of Michelle Obama's credit report, said its own systems "were not hacked or compromised in any way."
The perpetrators "had considerable amounts of information about the victims, including social security numbers and other sensitive, personal identifying information that enabled them to successfully impersonate the victims over the Internet," it said.The data also came from two others services, Equifax and CreditKarma.

The US Secret Service, which protects the president and his family, and the Federal Bureau of Investigation both said they were investigating the matter.FBI spokeswoman Jennifer Shearer said she could not provide any details on the probe or confirm the identities of the victims.Although they are supposed to be restricted, financial companies vetting individuals for loans and credit cards have easy access to the records.

Individuals can also obtain their own credit records online.It was not clear who posted the records. The data was placed on a website with a web address with the ".su" root indicating the Soviet Union -- an address still controlled by Russia.The website led with a quote from the US cable television series "Dexter" about a policeman-turned-serial killer: "If you believe that God makes miracles, you have to wonder if Satan has a few up his sleeve."