Authored by John Solomon via Circa.com,

Sen. Rand Paul, the former Republican presidential candidate and vocal champion of civil liberties, has received allegations that the Obama administration sought intercepted intelligence from the National Security Agency on him and other members of Congress and has asked President Donald Trump to conduct a formal investigation, Circa has learned.

Paul quietly asked for the probe nearly a month ago in a letter to Trump that was obtained by Circa.

"An anonymous source recently alleged to me that my name, as well as the names of other Members of Congress, were unmasked, queried or both, in intelligence reports of intercepts during the prior administration," Paul wrote Trump in a letter dated April 10. "In light of the revelations that the names of persons associated with the Trump campaign were unmasked, I believe the allegations that myself and other elected members of the legislative branch may have also been unmasked or caught in intelligence gathering warrants investigation."

The emergence of the letter, which also was copied to White House Chief of Staff Reince Priebus and senior Trump adviser Steve Bannon, comes after Circa recently reported that members of Congress and their staffs have been unmasked in NSA intelligence reports as frequently as once a month since President Obama loosened privacy protections back in 2011.

Sen. Rand Paul tweets about the unmasking allegations.

Did the Obama admin use warrantless "wiretapping" on other candidates besides @realDonaldTrump? https://t.co/h7rsjvNLHM — Senator Rand Paul (@RandPaul) May 5, 2017

Paul's letter offered no further detail on the source of the allegations of any specific incident or intercepts.

A source in the intelligence community told Circa on Friday that they were unaware of any unmaskings of NSA intercepts that occurred in 2016 when Paul was running for president that would have required a notification to Congress. The source did not know about prior years.

Usually if the intelligence community reveals the identity of a lawmaker in an NSA intercept, Congress gets what is known as a Gates notification.

Paul has been a critic of the government use of NSA intercepts to spy on Americans and championed other civil liberty causes, most famously conducting a 13-hour filllibuster in 2013 on the Senate floor to raise concerns that U.S. millitary could use drones to strike U.S. citizens on U.S. soil.