President Trump on Thursday criticized reports that he is now under investigation for obstruction of justice in connection with the firing of FBI Director James Comey, denouncing it as another "witch hunt" that is unfairly targeting him.

"They made up a phony collusion with the Russians story, found zero proof, so now they go for obstruction of justice on the phony story," Trump tweeted. "Nice."

Trump followed up about an hour later with another critical tweet: "You are witnessing the single greatest WITCH HUNT in American political history — led by some very bad and conflicted people!"

Trump appeared to be a responding to a Washington Post report that special prosecutor Robert Mueller "is interviewing senior intelligence officials as part of a widening probe that now includes an examination of whether President Trump attempted to obstruct justice, officials said."

While the Justice Department appointed Mueller to investigate Russian efforts to interfere in the 2016 presidential election — and any "collusion" with the Trump campaign — his assignment also includes "any matters that arose or may arise” from the Russia probe.

Comey told the Senate Intelligence Committee that he believes Trump fired him last month because he resisted a request to drop the Russia investigation, especially as it related to former national security adviser Michael. Flynn.

Trump said he fired Comey for poor performance, though he ealso reportedly told a group of Russian officials that the Comey dismissal would help get the Russia probe behind him. He also called Comey a "nut job."