0718 GMT January 18, 2019
Trump, who has long been angered over the probe, accused the country's top law enforcement officers – some of whom he appointed himself – of politicizing investigations in favor of Democrats and against his fellow Republicans, Reuters reported.
Trump has repeatedly complained about his treatment by federal investigators probing possible collusion between his campaign and Russia to sway the 2016 presidential election, and any actions to impede the investigation.
"The top Leadership and Investigators of the FBI 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 said on Twitter. The president praised "rank and file" FBI employees.
The timing of his latest salvo – two days after the FBI warned publicly against releasing the classified memo – was sure to worsen the president's frayed relations with agencies that are supposed to be politically independent.
A White House official said Trump was likely to give Congress approval to release the four-page document that has become a flashpoint in a wider battle between Republicans and Democrats over Special Counsel Robert Mueller's Russia probe.
The criminal probe grew out of the FBI's Russia investigation after Trump fired FBI director James Comey and Attorney General Jeff Sessions recused himself from the investigation. Russia has denied meddling in the election campaign. Trump, who has called Mueller's probe a political witch hunt, has denied any collusion or obstruction of justice.
The FBI expressed "grave concerns about material omissions of fact" in the Republican memo on Wednesday, in a rare public rebuke of the president and Republicans in Congress pushing to release the memo.
Democrats have depicted the memo, which was crafted by Republican members of the House Intelligence Committee, as misleading, based on a selective use of highly classified data and intended to discredit Mueller's work.
US Representative Adam Schiff, the top Democrat on the House intelligence panel, responded to Trump's tweets with his own Twitter message. "The country’s top elected leader has agreed to selectively and misleadingly release classified info to attack the FBI — that’s what would have been unthinkable a short time ago," he said.
There has been speculation that FBI Director Christopher Wray, appointed by Trump after he fired Comey, might resign if Trump allows release of the memo.
James Clapper, the former director of national intelligence, said Trump's attack on the FBI and Justice Department was the "pot calling the kettle black."
Republican efforts to release selective portions of classified information in the memo was a "blatant" political act, he told CNN.