Chinese billionaire businessman Jack Ma on Friday offered the United States 500,000 coronavirus test kits and a million masks, as the country faces a shortage of kits for diagnosing the potentially deadly disease.

In a statement on Twitter, the founder of e-commerce giant Alibaba said, "drawing from my own country's experience, speedy and accurate testing and adequate protective equipment for medical professionals are most effective in preventing the spread of the virus."

"We hope that our donation can help Americans fight against the pandemic!" he said in the statement, which was posted by the Jack Ma Foundation.

Ma, who is China's richest man, said that over the past weeks, his organizations had helped provide similar supplies to virus-hit countries such as Japan, South Korea, Italy, Iran and Spain. "The pandemic we face today can no longer be resolved by any individual country," Ma said. "We can't beat this virus unless we eliminate boundaries to resources and share our know-how and hard-earned lessons," Ma said.

The US government has come under heavy criticism for the slowness of testing for the virus, and public health officials have rebuked President Donald Trump for playing down the seriousness of the fast-spreading pandemic.

Joe Biden, the Democratic frontrunner in the race to face Trump in elections in November, slammed the lack of test kits on Thursday. "The administration's failure on testing is colossal, and it's a failure of planning, leadership and execution," the former vice president said.