US President Donald Trump has publicly slammed Attorney General Jeff Sessions, saying that Sessions does not understand what was happening under him at the Department of Justice.

"Jeff Sessions said he wouldn't allow politics to influence him only because he doesn't understand what is happening underneath his command position," Trump tweeted on Saturday. "Highly conflicted Bob Mueller and his gang of 17 Angry Dems (Democrats) are having a field day as real corruption goes untouched. No collusion!"