Washington: US President Donald Trump is set to approve the release of a controversial memo accusing the FBI of abusing its surveillance tools during its probe into alleged Russian collusion in the 2016 presidential election, setting up a clash with the intelligence agency. 

The approval for the release of such a memo, which is being opposed by the FBI, could come as soon as tonight, US media reported. A senior administration official told reporters aboard Air Force One that the president is expected to tell Congress that he has no objections to the release of the memo written by House Intelligence Chairman Devin Nunes. 

Requesting anonymity, the official said it is a Congressional process and that the decision was made after looking at the memo the last few days and making sure "it doesn't give away too much in terms of classification". "The president is ok with it," the official said. 

"I doubt there will be any redactions. It's in Congress' hands after that," the official said and refused to answer any further questions. Trump's reported decision comes a day after the FBI in an unusual move went public urging against release of the memo. Some White House official fear that this might result in the resignation of FBI Director Christopher Wray.