Washington (CNN) Hillary Clinton on Wednesday brushed off a report that her private email server contained classified intelligence from some of the U.S. intelligence community's most secretive programs.

The former secretary of state told National Public Radio that the report was a "leak" designed to harm her in the presidential race despite offering no evidence. And a spokesman for the Democratic presidential front-runner went so far as to publicly accuse investigators looking into her server as conspiring with Republican senators to embarrass her.

"As the State Department has confirmed, I never sent or received any material marked classified, and that hasn't changed in all of these months," she said. "This, seems to me, to be, you know, another effort to inject this into the campaign. It's another leak."

She also called an inspector general's letter a "continuation of an inter-agency dispute that has been going on now for some months."

Clinton was referring to a letter sent by Intelligence Community Inspector General I. Charles McCullough III to leaders on congressional intelligence committees last week detailing the findings from a review of Clinton's emails, a spokeswoman for the inspector general confirmed to CNN.

Two government agencies flagged emails on Clinton's server as containing classified information, the inspector general said, including some on "special access programs," which are a subset of the highest "Top Secret" level of classification, but are under subject to more stringent control rules than even other Top Secret information."

Clinton's spokesman, Brian Fallon, told Bloomberg that the campaign believes McCullough and Republican senators worked together to make sure the report would become public.

"It is suspect from the beginning that the intelligence community inspector general is continuing to reveal materials and surface allegations while the Justice Department review is going on," Fallon told Bloomberg. "It's completely fair to suspect that the intelligence community inspector general is not operating in good faith."

Fallon also appeared on CNN Wednesday morning to dispute the report. He argued on "New Day" that the information described as "classified" may be no more than a news article that was forwarded, although he ceded it is not entirely clear what classified material the report mentions.

Fallon argued that the crux of the issue is a dispute between the State Department and the intelligence community over what should be classified. He said the emails were not classified in the eyes of the State Department when they were sent to Clinton. Fallon also implied the inspector general has an ax to grind with Clinton.

There were several dozen emails in question beyond the two previously reported emails containing top secret information, according to the report.

Clinton's campaign and the State Department have long denied that any information was handled improperly, saying that the information and emails in question were all retroactively classified.

State also has noted that the same information can come from multiple sources, not all of which are classified.

State Department spokesman John Kirby said the department is still undergoing its review process, but any upgraded classification that is needed will be done.

"The State Department is focused on and committed to releasing former Secretary Clinton's emails in a manner that protects sensitive information," Kirby said in a statement. "No one takes this more seriously than we do. We have said repeatedly that we anticipate more upgrades throughout our release process. Our (Freedom of Information Act) review process is still ongoing. Once that process is complete, if it is determined that information should be classified as Top Secret, we will do so."

The Justice Department is investigating if classified information improperly ended up on Clinton's email server. The server contained correspondence between Clinton and a variety of aides and friends.

Republican lawmakers requested the inspector general investigate in March.

The Inspector General report was first reported by Fox News. It comes as the State Department is facing over a dozen Freedom of Information Act lawsuits related to information on or about Clinton's private email server.

On Wednesday, the department released a set of emails between top Clinton aides and an IT staffer to The Daily Caller and the advocacy group Cause of Action in one such suit.

Earlier in the week, the same plaintiffs received emails from Clinton aide Huma Abedin, now a top official on Clinton's presidential campaign, which show Clinton was given the option of using a State Department Blackberry for email purposes, but the option was dismissed.