WASHINGTON, Feb. 2 (Xinhua) -- U.S. President Donald Trump Friday ripped into Special Counsel Robert Mueller's ongoing Russia probe, accusing the country's top-level law enforcement officials of favoring Democrats.

"The top Leadership and Investigators of the FBI (Federal Bureau of Investigation) and the Justice Department have politicized the sacred investigative process in favor of Democrats and against Republicans -- something which would have been unthinkable just a short time ago," Trump tweeted.

The president is expected to approve Friday the publication of a controversial classified memo alleging the FBI and Justice Department abused their surveillance powers during the Russia probe, local media reported.

"'You had Hillary Clinton and the Democratic Party try to hide the fact that they gave money to Fusion GPS to create a Dossier which was used by their allies in the Obama Administration to convince a Court misleadingly, by all accounts, to spy on the Trump Team,' Tom Fitton, JW," Trump quoted the president of conservative watchdog Judicial Watch in a second tweet.

Fusion GPS is a Washington, D.C.-based commercial research and strategic intelligence firm that paid a former British spy to compile a dossier on Trump when he was a presidential candidate.

The president has read the memo and "is okay with it," a senior White House official Thursday told reporters traveling with Trump to West Virginia.

The memo, prepared by Devin Nunes, Republican chairman of the House Intelligence Committee, is said to be part of a bid to prove that the FBI and Justice Department are biased and out to get the president.

Nunes, who served on the Trump transition team, is widely seen as Trump's close ally.

Democratic lawmakers have called the memo misleading and part of an effort to undermine Mueller's probe into possible collusion between the Trump campaign and Russia during the 2016 elections.

The memo was meant to "sow conspiracy theories and attack the integrity of federal law enforcement as a means to protect President Trump," Senate Minority Leader Chuck Schumer said Thursday.

The Republican-controlled House Intelligence Committee Monday voted along party lines to approve the release of the four-page memo.

Two days later, the committee's Democratic ranking member, Adam Schiff, charged that Nunes hadn't sent the same memo to the White House that the full committee had voted on.

Jack Langer, a spokesperson for Nunes, confirmed that the memo had been edited, but said the changes included "grammatical fixes and two edits requested by the FBI and by the Minority (the Democrats) themselves."

The FBI, which objects to the memo's disclosure, said in a statement Wednesday that it has "grave concerns about material omissions of fact that fundamentally impact the memo's accuracy."