A United States court has confirmed that WikiLeaks founder Julian Assange is still being targeted by the Federal Bureau of Investigation more than five years after the anti-secrecy website's first publication of a secret diplomatic cable leaked by US soldier Chelsea Manning.

In a judgment handed down on March 4, 2015, US District Court judge Barbara Rothstein has stated that the FBI and the US Department of Justice are still pursuing an "ongoing criminal investigation of WikiLeaks" arising from the leaks of classified information by private Manning in early 2010.

In largely rejecting an application by the US Electronic Privacy Information Centre for release of documents under US freedom of information laws, Judge Rothstein accepted FBI and Justice Department claims that the disclosure of any information would prejudice a "multi-subject investigation" into WikiLeaks that is "still active and ongoing."

Judge Rothstein found that the FBI and Justice Department's National Security and Criminal Justice Divisions provided "sufficient specificity as to the status of the investigation, and sufficient explanation as to why the investigation is of long-term duration."

She also confirmed that the WikiLeaks investigation is "separate and distinct" from the investigation and prosecution of private Manning who was convicted by a US military court of espionage and other offences in July 2013 and sentenced to 35 years' imprisonment.