A WHO expert sent to China to probe the coronavirus hit out at US intelligence on Covid-19 as his team headed home with few answers about the origin of a pandemic that was forcing more clampdowns in some of the hardest-hit parts of the world, AFP reported.

The WHO mission to the ground zero city of Wuhan wrapped up on Tuesday without any concrete answers, with Washington again expressing scepticism about China's transparency and cooperation.

But WHO team member Peter Daszak tweeted: “Please don't rely too much on US intel: increasingly disengaged under Trump & frankly wrong on many aspects.” He said they worked “flat out under the most politically charged environment possible”.