WASHINGTON (AFP) - Donald Trump gave vent to frustrations over his mounting political problems Wednesday (May 17), declaring that no president in US history had been treated "more unfairly."

During a commencement address at the US Coast Guard Academy, Trump urged graduating cadets to follow his example and "fight, fight, fight. Never, ever, give up. Things will work out just fine."

"Look at the way I've been treated lately. Especially by the media. No politician in history, and I say this with great surety, has been treated worse or more unfairly. You can't let them get you down," he said.

The outburst came amid intensifying pressure on the president in the wake of his firing of James Comey as director of the FBI last week, in the midst of a probe into whether Trump's campaign colluded with Russian attempts to tilt the US election in his favour.

The Senate Intelligence Commitee announced Wednesday that they have asked Comey to testify.

The New York Times, citing sources close to Comey, reported on Tuesday (May 16) that Trump asked the FBI director in an Oval Office meeting to drop its probe of former national security adviser Michael Flynn.

A day earlier, the Washington Post, citing unnamed sources, reported that Trump had shared highly classified intelligence with Russian Foreign Minister Sergei Lavrov regarding an Islamic State of Iraq and Syria group terror threat.