There is growing concern around the lack of quarantine measures in place for bulk carrier cargo ships arriving in Australia from coronavirus hit countries like China and South Korea.

Crew members from these ships are currently able to enter Australia without any medical checks or screenings, if the ship has been at sea for more than two weeks.

A Current Affair was contacted by a Western Australian worker familiar with the port's quarantine system. He was unwilling to disclose his identity but wanted to blow the whistle on the potential risks the free flow of crews and products through Australian seaports poses to the country.

Crew members from carrier ships are currently able to enter Australia without any medical checks or screenings, if the ship has been at sea for more than two weeks (A Current Affair)

"There is no third party, ports authority, or WA government quarantine involved checking these crews as they come ashore," he revealed to A Current Affair.

Australia's seaports are extremely busy, and account for the majority of imports and exports. Unlike overseas flights, experts warn the passageways simply cannot be shut down safely.

"You can't get fuel any other way, you can't get goods here any other way, you can't get our coal, iron ore out of the country unless it's in a ship, we need to keep those lines open," Ports Australia CEO Mike Gallacher told A Current Affair.

Currently, it is up to the captains of cargo ships to make the call about whether any of the crew members are infected with coronavirus or pose a risk.

Professor Raina MacIntyre, the head of biosecurity at the Kirby Institute, warns this measure is not stringent enough, and seaports could act as corridors for coronavirus to enter Australia without stricter measures.

"The crew might be a reservoir of ongoing infection," she told A Current Affair.

Ports Australia CEO Mike Gallacher said seaports are crucial for Australia. (A Current Affair)

Concern about the potential coronavirus passageway is at the front of many people's minds in Karratha in the Pilbara region of Western Australia.

Karratha is a mining town of 23,000 and a mega export hub for our natural resources.

The whistle blower who contacted A Current Affair works at for one of the major resource companies operating in the Pilbara region. He told the program there are "zero checks at our site".

As of last week, the ports there were still operating at security level one, the lowest threat level. As the carrier ships from countries including China and South Korea dock in Karratha to load up, crew members are free to go into the township and visit local shops.

In a statement, Border Force told A Current Affair that ships from China, South Korea and Iran "will be subject to additional reporting requirements and restrictions on crew disembarking the vessel".

Australia's Mission to Seafarers organisation drives foreign crew members from ports to shopping centres around the country. (A Current Affair)

Despite the government rolling out extra measures last month, A Current Affair's Karratha mining source claims nothing's changed at his port.

"We have seen no extra border force or quarantine involvement on our wharfs. It is business as usual out here, crews come and go as they please as long as the captain deems them well," he said.

A Current Affair reporter Steve Marshall went to the region and found that many of the Karratha locals felt concerned about coming into contact with the crews from abroad who have not undergone any medical tests or precautionary measures.

"If this is as bad as everyone is saying it is then of course there should be some sort of quarantine," one local told A Current Affair.

"There probably should be checks put in place for some people coming from overseas, whether they are Chinese or Australian, it shouldn't matter who they are," another said.

International sea lanes are extremely busy and account for the majority of global trade. (A Current Affair)

Australia's Mission to Seafarers organisation drives foreign crew members from ports to shopping centres around the country. One volunteer driver told A Current Affair drivers have been told to stay one metre apart from ship crews and to report any signs of fever.

He also said several of his elderly colleagues have quit driving amid of the virus threat. Ports Australia CEO Mike Gallacher assured ship captains and companies are on notice to be up front about the health of their crew on arrival.

"There's no room for negotiation on it, they also know the significant penalties that exist for shipping lines that don't do the right thing running into many hundreds of thousands of dollars," he said.

In addition to captains, seafarer pilots are also being relied on to detect unwell crew members before piloting the ship into port. The issue with this is that neither seafarer pilots nor ship captains are medical professionals.

"Ideally you'd have someone who was qualified in public health screening to be doing that job," Professor MacIntyre from the Kirby Institute said.

Karratha is a mining town and mega export hub for our natural resources. (A Current Affair)

As a precaution, international ships are not allowed dock unless they've spent 14 days at sea, the globally accepted maximum incubation period of the COVID-19 virus.

Yet, there are cases emerging of patients not showing symptoms of the virus up until nearly a month.

"There's been reports of even up to 28 days… but by the same token it also means that the vast majority of cases - 99 per cent - are well and truly less than 14 days," infectious disease physician Peter Collignon told A Current Affair.

While that may come as a comfort, cases of asymptomatic carriers infecting communities unknowingly are now emerging.

"The problem is we are increasingly becoming aware of asymptomatic transmission which is people who become infected but do not have symptoms. Whether they go on to be transmitting virus after the quarantine period is the question," Ms MacIntyre said.

Making the complex situation even more difficult is the fact that experts like Mr Collignon say barring ships from high risk countries is simply not an option.

Closing the borders, he said, will do more damage than good as it will mean Australians are left without access to vital products such as medicines.

"That actually means you will cause more death by completely restricting trade and movement of people than from the virus itself," he said.

Seaports could act as corridors for coronavirus to enter Australia without stricter measures. (A Current Affair)

A spokesperson from the Australian Border Force issued A Current Affair the below statement:

Measures in place for maritime crew

· The ABF and the Department of Agriculture are working together to ensure that Australia's robust health protocols are fully enforced at the border.

· Before arriving in Australia, all commercial vessels are required to complete reporting about their biosecurity status. This reporting has been updated to include specific questions about COVID-19 (Coronavirus) risk factors.

a. The Department of Agriculture, Water and the Environment assesses all pre-arrival reporting, and where necessary, completes a human health inspection of international vessels.

· Following the Prime Minister's announcement yesterday all maritime crew are subject to the precautionary 14 day self-isolation period.

During this period crew are only able to disembark to conduct essential vessel functions and they must wear personal protective equipment while performing these functions.

These restrictions apply until 14 days has elapsed since the vessel or any person on-board left a foreign port. Unless crew are unwell or there is a suspected case of COVID-19 on-board.

· The arrangements put in place by the Australian Government will assist to safeguard the Australian community, while continuing to support Australia's international trade.

o Local port authorities may have implemented additional requirements over and above those set by the Government.