ABC News

Authorities have warned the pandemic may overwhelm the country's health system.(Supplied: ChildFund)

Papua New Guinea recorded its biggest daily spike of coronavirus cases, with another eight people diagnosed in Port Moresby.

In the past six days, 51 cases have been identified in the capital, bringing the country's total to 62.

The majority of the recent cases are linked to an outbreak at the Port Moresby General Hospital, where at least four technicians working at a COVID-19 lab tested positive.

Among the latest cases are three high school students and one university student, believed to have been identified in contact tracing from the hospital cases.

Hospital CEO Paki Molumi told local media the facility was being cleaned and would go into "emergency mode".

"We need to scale down services so that we clean out the entire hospital," Dr Molumi said.

"We will assess as we go along in the next two weeks."

PNG's Acting Health Secretary, Dr Paison Dakulala, told the ABC another three new cases confirmed overnight had also visited the hospital.

PNG's 'broken' health system may buckle

Port Moresby's General Hospital has been placed into "emergency mode" following the discovery of new cases.(ABC News: Bethanie Harriman)

There are concerns other cases may have been missed and people are being urged to report symptoms.

Prime Minister James Marape said Port Moresby would be placed under stage three restrictions, including a mandatory use of face masks.

Police and military will be used to advise people on the restrictions and how they should respond to COVID-19.

"Priority will be given to protecting our health workers, as well as police and military who will be involved in defending Port Moresby city from an explosion or blowout of COVID-19," he said.

Mr Marape said nightclubs may be banned, but churches, restaurants and bars would remain open.

"We're looking at how to readjust schools in the city — maybe morning classes and night classes for space."

Exact details of the new restrictions and how they will be enforced were yet to be released.

While the numbers may seem low, PNG's limited health infrastructure have authorities worried.

They have warned the city's coronavirus isolation centre may be full by the end of the month if the rise continues.

Countries with pre-existing conditions — poverty, limited healthcare, ineffective or corrupt governments — are fragile, and COVID-19 is threatening to push them to the brink of survival, writes Melissa Clarke.

David Manning, PNG's COVID-19 pandemic controller, said in a Government press release the rise was "of grave concern".

"Without strict compliance, cases are likely to rise within this month and this is showing to be true," Mr Manning said.

PNG Prime Minister James Marape has previously warned the country's health system would not "have the capacity to deal with a widespread outbreak".

Jonathan Pryke, director of the Pacific Islands program at the Lowy Institute, told the ABC in April that PNG's health system was "on the edge of breaking, if not already broken".