NEW YORK • United States President Donald Trump has blocked author Stephen King from following his tweets.

But Harry Porter author J.K. Rowling has come to the rescue of King, offering to forward the tweets to the horror king, who has consistently criticised the US leader over his policies.

"A Trump presidency scares me more than anything else," King told The Washington Post in September, before the presidential election in November.

When he found out on Tuesday that he had apparently been blocked, his initial thought was that it could be a prank. But he tweeted later: "Blocked! Condemned to an existential wasteland of Trumplessness!"

Rowling, who has also been critical of Mr Trump, is in the good books of King, who wrote a glowing review of Harry Potter And The Goblet Of Fire in 2000, noted Time magazine.

Mr Trump has also blocked other people, an act seen ironically as a badge of honour by some, since it implies that the President has noted the person's views.

Debate has swirled over whether it is unconstitutional for a US president to prevent certain Americans from seeing his public communication.