Anonymous leaks Bank of America e-mailsThe leak, which includes correspondence between staff at BoA subsidiary Balboa Insurance, details plans to delete sensitive documents.
It does not explain why the files were to be removed or how this supports Anonymous' accusation of criminality.
Bank of America has denied wrongdoing and called the claims "extravagant".
The company has been subject of rumours that its secrets would be leaked online for months.
But it was expected that Wikileaks would publish the secret documents, not a site associated with Anonymous.
Wikileaks connection In late 2010, Wikileaks founder Julian Assange said he planned to release documents in early 2011, which could bring down a well known bank.
Previously, he had claimed to be in possession of a hard drive containing internal documents from a senior Bank of America official.
The Wikileaks release has yet to appear, and it is unclear if those files are the same ones obtained by Anonymous.
One of the documents appears to show an employee of Bilboa Insurance asking a colleague to delete certain loan identifying numbers from their computer system.
No information is given about the reason for the deletion, or whether it was ultimately carried out.
An Anonymous member, posting updates on Twitter under the name OperationLeakS said the e-mails form the first part of a series of planned leaks that will prove Bank of America engaged in improper mortgage foreclosure practices.
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What is Anonymous?'Anonymous' describes itself as an 'internet gathering'. The term is used to describe a collective of people who come together online, commonly to stage a protest.
The groups vary in size and make-up depending on the cause. Members often identify themselves in web videos by wearing the Guy Fawkes masks popularised by the book and film V for Vendetta.
Its protests often take the form of disrupting websites and services.
The name Anonymous comes from a series of websites frequented by members, such as the anarchic image board 4Chan.
These sites allow users to post without having to register or provide a name. As a result, their comments are tagged "Anonymous".
In the past, members have staged high-profile protests against the Church of Scientology and plans by the Australian government to filter the internet content.
Many Anonymous protests tackle issues of free speech and preserving the openness of the net.
But BoA said the clerical and administration documents do not relate to foreclosures."We are confident that his extravagant assertions are untrue," a BoA spokesman said.
Leaked e-mailsThe e-mails were initially posted online online at http://bankofamericasuck.com.
That website has only been available intermittently, having been overwhelmed by requests.
Subsequently, sites mirroring the content have sprung up and the documents have also been released through peer-to-peer networks.
However, some of the torrents, such as the one hosted on the Pirate Bay, have been removed.
Anonymous members have engaged in a campaign of action against websites and companies that assisted the United States government in its attempt to isolate Wikileaks.
It has previously posted internal e-mails from computer security company HBGary and launched denial of service attacks against PayPal and Visa.
The leaked HBGary e-mails proved highly damaging to the firm, containing details of its secret work with several high-profile clients.
Bank of America stopped handling payments for Wikileaks, after it published leaked US embassy cables.
Firms are increasingly concerned about the prospect of disgruntled staff taking caches of sensitive e-mails with them when they leave, said Rami Habal, of security firm Proofpoint.
"You can't do anything about people copying the content," he said.
But firms can put measures in place, such as revoking encryption keys, which means stolen e-mails become unreadable, he added.