FBI director James Comey asked Justice Department to refute Trump's wiretapping claims, sources say

— -- FBI Director James Comey asked the Justice Department to publicly refute President Trump's assertion that his predecessor, President Obama, ordered a wiretap of Trump's phones prior to the November 2016 election, government sources familiar with Comey's thinking confirm to ABC News.

Comey was concerned the president's tweets -- which he believes are inaccurate -- created the impression that the FBI acted improperly, and he wanted to set the record straight, the sources said.

The FBI and Department of Justice declined to comment.

Trump, who offered no evidence for his claims, tweeted Saturday that Obama was a "bad (or sick) guy," and likened the alleged taps to Watergate.

In a statement Sunday, White House press secretary Sean Spicer called "reports concerning potentially politically-motivated investigations" prior to the election "very troubling."

The president has requested that congressional intelligence committees probing Russian involvement in the 2016 election also examine "whether executive branch investigative powers were abused in 2016," Spicer said.

"Neither the White House nor the president will comment further until such oversight is conducted," he added.

An Obama spokesperson yesterday denied the former president's involvement, saying: "A cardinal rule of the Obama administration was that no White House official ever interfered with any independent investigation led by the Department of Justice. As part of that practice, neither President Obama nor any White House official ever ordered surveillance on any U.S. citizen. Any suggestion otherwise is simply false."

It's the attorney general, not the president, who signs off on applications for a wiretap warrant. In foreign intelligence cases, those applications must be approved by the FISA court -- a secret tribunal with the authority to grant warrants for electronic surveillance of any "foreign power or agent of a foreign power" engaged in espionage or terrorism.

Attorney General Jeff Sessions has pledged to recuse himself from all DOJ investigations related to the 2016 presidential campaigns.

This isn't the first time Comey, who has led the FBI since 2013, has been thrust into the spotlight over election-related issues.

In October, just weeks before Election Day, Comey made the controversial decision to announce that the bureau was re-opening its investigation into Democratic nominee Hillary Clinton after uncovering additional emails in her private email server during her tenure as secretary of state.

The FBI later concluded that the additional emails did not impact the case and Comey told lawmakers he wanted to "supplement the record" so as not to "mislead" the American people.