President Donald Trump Friday suggested that the knowledge that an FBI agent altered a document leading to a Foreign Intelligence Surveillance Act (FISA) court granting permission to spy on campaign aide Carter Page went "all the way" to then-President Barack Obama.

"They were spying on my campaign and it went up to the top and everybody knows it, and now we're going to find out," Trump said during an extensive call-in interview with Fox News' "Fox and Friends."

"This was spying on my campaign, something that has never been done in the history of our country," he added. "This was an overthrow attempt at the presidency. They tried to overthrow the presidency. This is a disgrace...I'm not surprised to see it. It is just starting to come up. I think this is nothing compared to what you will see next couple of weeks. These people are sick."

According to CNN, the FBI official is under criminal investigation after allegedly altering the document, a finding that is expected to be included in Justice Department Inspector General Michael Horowitz's review of the agency's effort to obtain warrants against Page.

Horowitz will release the report Dec. 9, and testify before the Senate Judiciary Committee two days later. Horowitz turned over evidence to John Durham, the federal prosecutor appointed by Attorney General William Barr to conduct a probe of intelligence gathered for the Russia investigation by the FBI, the CIA, and other agencies.

"What you're going to see I predict will be perhaps the biggest scandal in the history of our country, political scandal," said Trump. "I purposely stay out. I tell (Attorney General) Bill Barr to handle everything. I wouldn't have to. I could get very much involved but I purposely don't. I haven't, and you know what? It is better that way I guess."

The report on the FISA warrant is "historic," said Trump. "Even more importantly you have Durham, coming out, shortly thereafter. He is the U.S. Attorney and he has already announced it is criminal. And we'll see what happens. But I'll tell you what, you have a lot of very, very bad people. You know a lot of people say deep state. I don't like to use the word deep state. I say they're really bad, sick, people."

Trump refused to say who has told him that the scandal goes to the "highest levels of government," but that he can "only say that we have a lot of information that a lot of bad things happened."