US President Donald Trump has cancelled segments of the Republican National Convention scheduled for Florida in August, citing a “flare-up” of the coronavirus.

Convention events will still be held in North Carolina.

“To have a big convention is not the right time,” Mr Trump said of Jacksonville.

The cancellation is a major setback for Mr Trump ahead of the November 3 presidential election. He was to formally accept the Republican nomination to run for president in a major speech at the Florida convention.

Mr Trump said he would deliver an acceptance speech – although he has offered no details about where or when that might happen.

“I’ll still do a convention speech in a different form, but we won’t do a big, crowded convention,” he said.

“I care deeply about the people of Florida and everywhere else, frankly, in this country and even in the world who would be coming into the state. And I don’t want to do anything to upset it.”

Coronavirus cases are surging across the US, topping 4 million on Thursday – and growing by an average of more than 2600 every hour.  Florida has been hit especially hard, with day after day of more than 10,000 new infections.

Mr Trump moved parts of the national convention to Florida in June, amid a dispute with North Carolina’s Democratic leaders about holding an event indoors with supporters without masks.

Earlier in the month he had defied warnings from health authorities to hold a campaign rally in Tulsa, Oklahoma. Experts warned the rally – Mr Trump’s first since the pandemic lockdown and booked for a 20,000-capacity stadium – could be a virus “super-spreader”.

In the end, about 6000 people attended. But Tulsa authorities still reported a spike in COVID infections two weeks later.

“The past few days we’ve had almost 500 cases, and we know we had several large events a little over two weeks ago, which is about right. So I guess we just connect the dots,” Tulsa Health Department executive director Bruce Dart said.

Even Mr Trump’s alternative plans for the convention in Florida have been steadily scaled back as virus cases have spiked in the state and across the country.

A small subset of GOP delegates will still gather in Charlotte, North Carolina, to formally renominate Mr Trump on August 24.

-with AAP