President Trump said Tuesday that it would be illegal and unprecedented if the FBI had "spies in my campaign" during the 2016 election, and that he wants "to make sure that there weren't" any.

Trump's comment came on the heels of a Monday-evening statement from the White House that announced chief of staff John Kelly would lead efforts to deliver investigative Russia-probe documents to Congress.

"A lot of people are saying they had spies in my campaign," Trump told reporters at the White House Tuesday. "If they had spies in my campaign, that would be a disgrace for this country. That would be one of the biggest insults that anyone's ever seen, and it would be very illegal, aside from everything else. It would make probably every political event ever look like small potatoes."

Trump expressed uncertainty about whether there actually were "spies" on his campaign, adding, "we want to make sure that there weren't. I hope there weren't, frankly."

On Monday, Trump summoned FBI Director Christopher Wray, Deputy Attorney General Rod Rosenstein, and Director of National Intelligence Dan Coats for a meeting to discuss reports of an FBI informant linked to his campaign.

Trump tweeted on Sunday afternoon that he would "officially" ask "that the Department of Justice look into whether or not the FBI/DOJ infiltrated or surveilled the Trump Campaign for Political Purposes."

Trump left the Monday meeting with reassurance that the Justice Department's inspector general would look into the matter, and that the various agencies would meet with Kelly about the delivery of documents to Congress.

Trump said Tuesday that the gathering was "just a very routine meeting."

"Gen. Kelly's going to be setting up a meeting between Congress and the various representatives and they'll be able to open up documents, take a look and find out what but if they had spies in my campaign, during my campaign for political purposes, that would be unprecedented in the history of our country," he said.

House Intelligence Committee Republicans, led by chairman Rep. Devin Nunes, R-Calif., have sought unsuccessfully to see certain documents on the FBI's probe of possible Trump campaign collusion with Russia, including on its use of an informant.

Following initial reports of an FBI informant, Trump tweeted last week that it would be “bigger than Watergate” if there was an “embedded informant” on the campaign. Subsequent reporting indicated the informant was Cambridge University professor Stefan Halper, who was not embedded in the campaign but sought out meetings with campaign advisers Carter Page, George Papadopoulos, and Sam Clovis.

Nunes suggested over the weekend there may have been more than one informant.

Before the Monday meeting with Trump, Rosenstein on Sunday evening asked that the Justice Department inspector general review Trump's assertion that there may have been politically motivated spying on his campaign. The review will accompany an ongoing inspector general probe of the FBI's use of an opposition research dossier compiled by former British spy Christopher Steele, used to obtain a 2016 surveillance order against Page.

Halper has a pre-campaign relationship with White House economic adviser Peter Navarro, who reportedly recommended him for an administration job last year.