Anti-secrecy site WikiLeaks informed the United States in advance of tens of thousands of new document releases but ignored US appeals not to make them public, the State Department said on Thursday.
The remarks come after WikiLeaks accused a journalist with the Guardian of leaking the passwords to a trove of US diplomatic cables containing the names of protected sources, charges denied by the British newspaper.
"Wikileaks did advise us of the impending release of information and of its intention to continue to release classified documents," State Department spokeswoman Victoria Nuland said.
"We have made clear our views and concerns about illegally disclosed classified information and the continuing risk to individuals and national security that such releases cause," Nuland said in a statement.
"Wikileaks has, however, ignored our requests not to release or disseminate any US documents it may possess and has continued its well-established pattern of irresponsible, reckless, and frankly dangerous actions," she said.
"We are not cooperating with them," Nuland said during a visit to Paris with US Secretary of State Hillary Clinton.
The United States has warned that the release of confidential and secret documents, which began last November after WikiLeaks obtained 250,000 US diplomatic cables, puts at risk US national security and individuals who speak to US diplomats.
In London, WikiLeaks said "a Guardian journalist has, in a previously undetected act of gross negligence or malice, and in violation of a signed security agreement with the Guardian's editor-in-chief Alan Rusbridger, disclosed top secret decryption passwords to the entire, unredacted, WikiLeaks Cablegate archive".
"We have already spoken to the (US) State Department and commenced pre-litigation action. We will issue a formal statement in due course," WikiLeaks added, in a statement posted on Twitter.
The Guardian, one of a handful of newspapers that began publishing redacted cables last year, said WikiLeaks shared the documents through a secure server for a period of hours before taking the server offline and removing the files.
"But unknown to anyone at the Guardian, the same file with the same password was republished later on BitTorrent, a network typically used to distribute films and music," the newspaper reported.
The Guardian went on to deny, in an official statement, allegations that the password had been released through its book, "WikiLeaks: Inside Julian Assange's War on Secrecy", published in February.