U.S. President Donald Trump was on Wednesday back at work in the Oval Office of the White House just six days after testing COVID-19 positive, despite warnings that his return could put others at risk. 

The behavior of the president, who has faced fierce criticism for his handling of the pandemic, is under scrutiny as the number of positive cases climbs among people working at the White House. 

After contradictory statements whether the president was back at work on Tuesday, a senior administration official told AFP that Trump was present Wednesday with an "extremely limited" number of staff in his office. 

Trump, who was hospitalized Friday with the virus that has killed over 210,000 in the U.S., arrived by an outside door to avoid passing through the crowded corridors of his residence, the official said. 

"Was just briefed on Hurricane Delta," the president tweeted, eager to project his return as a personal triumph over the disease as he trails badly in polls against Democratic challenger Joe Biden. Trump's illness, like his dismissive stance on the virus, has fueled multiple controversies, including his made-for-television exit from the hospital on Monday. 

Just after stepping off a helicopter at the White House, he climbed the stairs of his residence and pulled off his face mask, a tool against the virus that he has frequently downplayed. 

"Don't let (COVID-19) dominate you. Don't be afraid of it," he urged Americans in his homecoming speech, despite the U.S. having the largest total number of coronavirus infections and deaths in the world. 

White House physician Sean Conley said on Wednesday that the president's "physical exam and vital signs, including oxygen saturation and respiratory rate, all remain stable and in normal range." 

"He's now been fever-free for more than 4 days, symptom-free for over 24 hours, and has not needed nor received any supplemental oxygen since initial hospitalization," Conley disclosed, adding that Trump's lab results from Monday "demonstrated detectable levels" of COVID-19 antibodies. 

In a video recorded from the White House and posted on Twitter in the evening, Trump touted the therapeutic and medical treatment that he has been receiving and called his infection of the virus "a blessing in disguise."

Responding to the remarks, 2020 Democratic presidential nominee Joe Biden told reporters in Wilmington, Delaware that he hopes Trump stays healthy but the former U.S. vice president again criticized his Republican opponent's attitude towards the disease. 

"I think it's a tragedy the president deals with COVID like it is something not to be worried about when already 210,000 people have died," Biden added. 

(with input from agencies)