In a statement to ABC News, Hrafnsson said the cables offer additional proof that American diplomats were asked to engage in intelligence gathering, an allegation the State Department denies.
"The latest release from the embassy cables reveals U.S. embassies were asked to gather information on key infrastructure and resources without the knowledge of, or consultation with, their host governments," Hrafnsson told ABCNews.com.
"This further undermines claims made by the U.S. government that its embassy officials do not play an intelligence gathering role," he said.
Though Assange has not been arrested on charges relating to the released cables, U.S. Attorney General Eric Holder said the release of the documents had put the United States at risk and said he authorized a criminal investigation into Assange.
"The national security of the United States has been put at risk; the lives of people who work for the American people has been put at risk; the American people themselves have been put at risk by these actions that are, I believe, arrogant, misguided and ultimately not helpful in any way. We are doing everything that we can," Holder said.
"We have a very serious, active, ongoing investigation that is criminal in nature. I authorized just last week a number of things to be done so that we can hopefully get to the bottom of this and hold people accountable, as they -- as they should be."