WASHINGTON, United States (AFP) — United States (US) President Donald Trump went on an extraordinary social media spree into the early hours of Tuesday, posting dozens of conspiracy theories and crude memes attacking his opponents.

The intense outburst on Truth Social came amid growing public scrutiny of the 79-year-old Republican’s health.

As Trump deals with the economically damaging impasse with Iran and prepares to fly later Tuesday for a summit in China, his attention was elsewhere in the night-time flurry.

In a span of just three hours around midnight Monday, Trump posted over 50 times, almost exclusively re-sharing videos and screenshots from supporters’ accounts, plus artificial intelligence-created memes.

Two posts called former Democratic president Barack Obama a “traitor” and a “DEMONIC FORCE”. Others called for Obama and other Trump critics to be arrested.

Multiple posts urging prosecution tagged Todd Blanche, a former Trump criminal defence lawyer who has been appointed acting US attorney general and is reportedly working to accelerate prosecutions of Trump critics.

Many of Trump’s posts reiterated his false claim that the 2020 election was stolen from him, including made-up assertions that voting machine manufacturers switched ballots cast for him to the actual winner, Democrat Joe Biden.

“The CIA knew what these machines were capable of and brushed it under the rug to control election outcomes,” read one post on his account.

He also shared at least two original posts signed “President DJT”: one cryptically saying the US was “going to talk” with Cuba and another — over 400 words long — defending his costly renovation project of the Lincoln Memorial Reflecting Pool.

In a recent Washington Post/ABC News/Ipsos poll, 59 per cent of respondents said they believed Trump lacked the mental capacity to lead the country, while 55 per cent said he was not physically fit.

Trump, the oldest president ever elected to the presidency, insists he is in top shape.

“I feel the same as I did 50 years ago. It’s crazy,” he asserted on Monday.

The White House announced on Monday that the president would undergo a medical and dental examination on May 26 at Walter Reed National Military Medical Center, near Washington.

It will be his third such visit since returning to the White House a year and a half ago.