Former US presidential candidate Herman Cain has died of COVID-19, weeks after attending a Trump rally in Oklahoma without wearing a mask.

Mr Cain’s death was confirmed via his official Twitter account.

The 74-year-old cancer survivor tested positive for the virus on June 29, and had been in hospital since July 1.

Mr Cain, a former chief executive of Godfather’s Pizza and a co-chair of Black Voices for Trump, briefly topped the polls for the Republican nomination for president in 2012. His last public appearance was at Mr Trump’s June 20 rally in Tulsa, Oklahoma.

“You’re never ready for the kind of news we are grappling with this morning. But we have no choice but to seek and find God’s strength and comfort to deal with it,” Dan Calabrese wrote on Mr Cain’s official website on Thursday (local time).

“Herman Cain – our boss, our friend, like a father to so many of us – has passed away.”

Tweet from @THEHermanCain

The President’s campaign said at the time that Mr Cain did not meet Mr Trump at the Tulsa rally.

“We knew when he was first hospitalised with COVID-19 that this was going to be a rough fight,” read an article posted on the Twitter account.

In a condolence tweet, Mr Trump described Mr Cain as “a powerful voice of freedom and all that is good”.

“Herman had an incredible career and was adored by everyone that ever met him, especially me,” Mr Trump wrote.

“He was a very special man, an American Patriot, and great friend.”

Tweet from @realDonaldTrump

It has not been revealed where Mr Cain caught COVID-19.

“I realise people will speculate about the Tulsa rally, but Herman did a lot of travelling the past week, including to Arizona where cases are spiking,” Dan Calabrese, who has been editor of HermanCain.com, wrote when Mr Cain was taken to hospital.

“I don’t think there’s any way to trace this to the one specific contact that caused him to be infected. We’ll never know.”

Even after announcing his diagnosis, Mr Cain had expressed support for the Trump administration’s decision not to require people to wear masks at an Independence Day celebration at Mount Rushmore.

“Masks will not be mandatory for the event, which will be attended by President Trump. PEOPLE ARE FED UP!” he tweeted.

The tweet was deleted after Cain’s death.

On Wednesday, a tweet from his account suggested scepticism about a COVID vaccine was justified because the US government and the media had “incinerated their credibility”. It linked to a post on Mr Cain’s website that argued that there was “no way of knowing the truth” about the likely safety of a vaccine.

-with agencies