Deputy Attorney General Rod Rosenstein asked the Justice Department's inspector general Sunday to review whether there was improper politically motivated surveillance of the Trump campaign in 2016.

Rosenstein made the request shortly after a tweet from President Trump saying 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."

In a statement, Rosenstein said: “If anyone did infiltrate or surveil participants in a presidential campaign for inappropriate purposes, we need to know about it and take appropriate action." The attorney general, Jeff Sessions, has recused himself from Russia-related matters.

Justice Department spokeswoman Sarah Isgur Flores added, "The Department has asked the Inspector General to expand the ongoing review of the FISA application process to include determining whether there was any impropriety or political motivation in how the FBI conducted its counterintelligence investigation of persons suspected of involvement with the Russian agents who interfered in the 2016 presidential election."

"As always," Flores said, "the Inspector General will consult with the appropriate U.S. Attorney if there is any evidence of potential criminal conduct."

White House spokespeople did not immediately respond to requests for comment Sunday afternoon on what probe Trump would like to see.

In March, Justice Department Inspector General Michael Horowitz said he would review the FBI's use of an opposition research dossier compiled by former British spy Christopher Steele to get a 2016 Foreign Intelligence Surveillance Court order to surveil former Trump campaign adviser Carter Page, though Horowitz referenced neither by name.

Horowitz said the review initiated in March was "in response to requests from the Attorney General and members of Congress" following the February release of a memo by House intelligence Committee Republicans outlining what they consider abuse of surveillance powers against Page.

In a series of tweets this weekend, Trump blasted special counsel Robert Mueller's probe of possible Trump campaign collusion with Russia as a "witch hunt," alleged a double standard with the FBI's treatment of former Secretary of State Hillary Clinton, his 2016 election rival, and demanded that the Justice Department provide congressional Republicans documents on surveillance of his campaign.

Following initial reports of an FBI informant linked to his campaign, Trump wrote on Twitter last week that it would be “bigger than Watergate” if there was an “embedded informant” on the campaign, and tweeted a quote that "Apparently the DOJ put a Spy in the Trump Campaign."

Subsequent reporting indicated the informant was a Cambridge University professor, who was not embedded in the campaign but sought out meetings with campaign advisers Page and George Papadopoulos, and with Trump campaign co-chair Sam Clovis.