US President Donald Trump has hit back at Robert De Niro, calling him a "very low IQ individual" in a series of tweets.
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"Robert De Niro, a very low IQ individual, has received to [sic] many shots to the head by real boxers in movies. I watched him last night and truly believe he may be 'punch-drunk.'
"I guess he doesn't realize the economy is the best it's ever been with employment being at an all time high, and many companies pouring back into our country. Wake up Punchy!" the US President wrote.
Oscar-winning actor De Niro issued an expletive-laden denunciation of Mr Trump during the live television broadcast of the Tony Awards ceremony on Sunday.
"I'm gonna say one thing. F**k Trump," he said, without any preamble.
With the audience of theatre actors, directors and producers shrieking and rising to their feet in applause, he said: "It's no longer down with Trump. It's f**k Trump."
De Niro, a noted liberal, has been increasingly critical of Mr Trump, a Republican, at smaller show business events, but none have the high profile and audience of the Tony Awards.
The F-bomb was bleeped by the CBS network for millions of television watchers at home. But it was heard by those in the audience and journalists covering the awards show, which honours the best of Broadway theatre, and it quickly became the top trending item on Twitter.