TULSA, UNITED STATES (AFP) - Six members of an advance campaign team working in Tulsa ahead of Donald Trump's Saturday rally (June 20) have tested positive for Covid-19, his campaign said, hours before the president was set to take the stage.

The announcement was likely to further fuel concerns that the rally, Trump's first since the pandemic brought a halt to major on-the-ground political campaigning, could be a "super-spreader" event as the coronavirus proves resilient in several states and cities including Tulsa.

"Per safety protocols, campaign staff are tested for Covid-19 before events," Tim Murtaugh, the Trump campaign's communications director, said in a statement.

"Six members of the advance team tested positive out of hundreds of tests performed, and quarantine procedures were immediately implemented," Murtaugh said.

"No Covid-positive staffers or anyone in immediate contact will be at today's rally or near attendees and elected officials."

Crowds of Trump supporters are converging on Tulsa for the president's rally, which is being held at an indoor arena that seats about 20,000 people.

Supporters have already begun streaming into the venue.

According to the campaign, all rally attendees are being given temperature checks, facemasks and hand sanitiser.

Some Trump officials have said use of masks is requested but not mandatory, and White House Press Secretary Kayleigh McEnany said she will not wear a mask at the rally.

Critics, including Tulsa city officials, have expressed concern that the event contravenes several guidelines that the US government's Centers for Disease Control and Prevention have issued about large indoor venues, social distancing and mask use.