WASHINGTON (REUTERS) - President Donald Trump's national security adviser, Robert O'Brien, returned to work at the White House on Tuesday (Aug 4) following his recovery from a mild case of Covid-19, a National Security Council spokesman said.

O'Brien "has already met with the President, who warmly welcomed him back to the West Wing," spokesman John Ullyot said in a statement.

"He has been cleared by doctors after two negative tests for the virus, and has been asymptomatic for over a week," Ullyot said.

The White House announced last week that O'Brien, 54, had tested positive for the novel coronavirus and showed mild symptoms. O'Brien worked from home during his quarantine, Ullyot said.

O'Brien was not the first person who worked at the White House to test positive for the virus.

A US military member who serves as a presidential valet at the White House tested positive in May as did Vice-President Mike Pence's press secretary.