U.S. President Donald Trump will not invoke executive privilege to block former FBI Director James Comey's much-anticipated testimony before Congress this week, his first since Trump abruptly fired him early last month.

"In order to facilitate a swift and thorough examination of the facts sought by the Senate Intelligence Committee, President Trump will not assert executive privilege regarding James Comey's scheduled testimony," White House spokeswoman Sarah Sanders told reporters on Monday.

Comey was leading a Federal Bureau of Investigation probe into alleged Russian meddling in last year's U.S. presidential election and possible collusion by Trump's campaign when the president fired him last month.

Presidents can assert executive privilege to prevent government employees from sharing information.

If Trump had asserted executive privilege over Comey, it would have likely created the perception that the administration was seeking to hide information about the FBI's Russia investigation.

It has been reported that Comey plans to talk about conversations in which Trump pressured him to drop his investigation into former national security advisor Mike Flynn, who was fired for failing to disclose conversations with Russian officials.

Both Trump's fellow Republicans and Democrats from the intelligence panel said they intended to grill Comey about whether Trump tried to get him to back off the investigation.

Comey's appearance before the Senate Intelligence Committee as part of its Russia-related investigation will be his first public testimony since his firing on May 9.

It is overshadowing other events in Washington, threatening to dampen already flagging momentum for Trump's legislative agenda of rolling back President Barack Obama's healthcare reforms and overhauling the tax code.

U.S. intelligence officials have said Russia tried to interfere in the election to sway the vote in Trump's favor, a charge the Kremlin has repeatedly denied. Trump has denied any collusion between his campaign and Russia.

Comey's appearance will be carried on live television. News stations, including Fox News Channel, will carry the hearing. Variety reported on Monday that at least two U.S. networks, ABC and CBS, had made the unusual decision to break into their daytime programming to carry it.

Senator Chuck Schumer, the top Democrat in the Senate, said he expected Comey's testimony would not be his last before Congress.

"I know the Senate Judiciary Committee has made a similar request of Mr. Comey and I support their request," Schumer said in remarks as the Senate reopened on Monday after a weeklong recess.