A witness has told 60 Minutes he saws tonnes of gloves, masks, gowns, sanitiser and other vital medical supplies being packaged to be shipped out of Australia to China.

It comes after Australian healthcare workers have reported shortages of important Personal Protective Equipment (PPE) in hospitals across the country.

The anonymous witness worked at Greenland, a Chinese-owned property development company in Sydney.

He told 60 Minutes reporter Liz Hayes he saw boxes of vital medical equipment being prepared to be sent to China in January and February this year.

"Meeting rooms, lunch rooms and the boardroom, starting to be filled with different types of items getting unpackaged and repackaged and labelled," he told 60 Minutes.

"It definitely rose my suspicion. The concern to me is if all these medical items leave the country, what's left for us?"

(Nine)

The man says employees of the company were asked to procure different medical items from shops and pharmacies, and that full-time employees were utilised in the packing and repackaging of the items.

"It is very unsettling that essential equipment can just leave our borders in massive commercial quantities," he said.

60 Minutes' witness saw masks, gowns and goggles packaged and shipped from Australia to China. (Nine)

But what 60 Minutes' witness saw in one Sydney office was being repeated in companies around the world.

In just two months, it is estimated China amassed an estimated 2.4 billion pieces of protective equipment, including more than two billion masks.

In an email to Sydney staff at Chinese-backed company Poly Developments and Holdings, employees were told to urgently find masks anywhere they could, encouraging them to buy from pharmacies across Sydney.

"If you have time please drop by your local pharmacy to check if there are any 3MN95 or 8210 masks for sale," the email obtained by 60 Minutes reads.

(Nine)

On February 24, another Sydney-based Chinese company, Risland, sent 90 tonnes of medical protection equipment to China.

The Australian government last week banned the non-commercial export of PPE such as face masks, hand sanitiser, gloves and gowns.

But for Australian healthcare workers it could be too late – as shortages are reported by hospital workers nationwide, with face-mask stocks already dangerously low after January's bushfire crisis.

60 Minutes reporter Liz Hayes. (Nine)

60 Minutes' witness says the export ban is good, but comes too late.

"I feel like the horse has bolted. We could have been more proactive. We could have had some sort of contingency plans in place for situations like this," he said.

"I think in a time of crisis, we all have a responsibility to do something, and I felt that I had to do something. It just didn't sit with me that this type of thing could happen. I couldn't just watch it and just stay silent."

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