Two people in their 80s are confirmed dead from the coronavirus outbreak aboard the Diamond Princess cruise ship, according to Japanese public broadcaster NHK.

The news comes as an infectious disease specialist who spent a day aboard the cruise ship took to Youtube to describe the “completely chaotic” scenes on the cruise ship on which “bureaucrats were in charge”.

Having previously worked on containing Ebola, SARS and cholera, Japanese professor Kentaro Iwata said he was not the only expert fearful of becoming infected from visiting the contaminated cruise ship.

Other medical professionals could only spend a few days there before needing to disembark – and for good reason, Dr Iwata said.

It comes amid growing global criticism over the decision to keep passengers on the vessel.

Dr Iwata said there was no clear demarcation line between infected people and non-infected people.

“There was no distinction between the green zone which is free of infection and the red zone which is potentially contaminated by virus,” he said in a video posted to YouTube.

Passengers appeared to come and go as they please including crew and health authorities who were walking around and going about their daily business without taking precautions against the virus, he said.

There have been more than 540 confirmed cases on board Diamond Princess which was carrying 2666 guests up until the United States on Monday evacuated 328 Americans on charted flights back home.

Earlier this week, the US Centers for Disease Control and Prevention questioned whether Japan’s “extraordinary efforts” to quarantine the ship were enough.

“CDC’s assessment is that it may not have been sufficient to prevent transmission among individuals on the ship,” the CDC said.

“The rate of new infections on board, especially among those without symptoms, represents an ongoing risk.”

• Related: More positive tests thwart evacuation plans, as travel ban extension looms

Dr Iwata recalled an incident where someone who had a fever walked over to the medical centre while having on an N95 mask but nothing was done to stop the spread of infection “between his room and the medical room”.

To make matters worse, the medical officer he greeted “had completely given up protecting herself” as she had coronavirus, Dr Iwata said.

“Everywhere could have virus and everybody was not careful about it.”

Thousands of passengers remain stuck on the Diamond Princess. Photo: Getty

Terrified of passing the coronavirus on to his family, Mr Iwata said he will isolate himself for the next two weeks to avoid potentially infecting other people.

“That is very likely to occur if you keep zero infection control inside the ship,” he said.

Dr Iwata slammed the cruise ship as “completely inadequate in terms of the infection control”.

“There was no single professional infection control person inside the ship and there was nobody in charge of infection prevention as a professional,” he said.

“The bureaucrats were in charge of everything.”

Dr Iwata said he spoke to Japan’s Minister of Health, Labor and Welfare Katsunobu Kato but he seemed “very unhappy” when he suggested that more needed to be done to stop secondary transmissions.