China reported a big drop in new coronavirus cases on Thursday, fuelling hopes the epidemic is nearing its peak, but Japan faced a growing crisis as two passengers from a quarantined cruise ship died.

Meanwhile, US President Donald Trump expressed confidence that China is "trying very hard" in its handling of the coronavirus outbreak, he said in a television interview.

"Well, I am confident that they are trying very hard," Trump said in an interview with Fox 10 Phoenix. "I think the numbers are going to get progressively better as we go along."

The death toll in China hit 2,118 as 114 more people died, but health officials reported the lowest number of new cases there in nearly a month, including in the hardest-hit province, Hubei.

More than 74,000 people have been infected in China and hundreds more in some 25 countries, with Iran reporting two deaths, the first fatalities in the Middle East.

In Japan, a man and a woman in their 80s who had been aboard the Diamond Princess have died, local media reported, citing a government source.

A World Health Organisation official noted the progress in China but warned it had not reached a turning point just yet.

Chinese officials said this week that their drastic containment efforts, including quarantining tens of millions of people in Hubei and restricting movements in other cities nationwide, have started to pay off.

"After arduous efforts, the situation is changing for the better," Foreign Minister Wang Yi said at a meeting with Southeast Asian counterparts in Laos late on Wednesday, according to the official Xinhua news agency.

Hubei and its capital Wuhan — where the virus is believed to have emerged in December — are still "severely affected" by the epidemic, Wang said.

"But the situation is under effective control, while other regions are embracing comforting news," he said.

'Not turning point'

More than 600 new infections were reported in Wuhan — the lowest daily tally since late January, and well down from the 1,749 new cases the day before.

The national figure has now fallen for three days in a row.

Chinese authorities placed Wuhan, a city of 11 million people, under quarantine on January 23 and quickly locked down the rest of Hubei in the days that followed.

Cities far from the epicentre have limited the number of people who can leave their houses for groceries, while villages have sealed themselves off from outsiders.

Richard Brennan, regional emergency director at the World Health Organisation, said China was making "tremendous progress in a short period of time" but cautioned that it was not over just yet.

"Trends are very encouraging but we are not at a turning point yet," Brennan told a press conference in Cairo.

'Chaotic' cruise quarantine

While China touts progress in its fight against the COVID-19 epidemic, Japan's government faces criticism over quarantine measures on the Diamond Prince cruise ship.

The huge vessel moored in Yokohama is easily the biggest coronavirus cluster outside the Chinese epicentre, with 621 positive cases confirmed among the passengers and crew — one sixth of the total.

On Wednesday, 443 passengers disembarked from the ship after testing negative for the COVID-19 virus and not showing symptoms during a 14-day quarantine period. The complete removal of the passengers was expected to last at least three days.

More passengers left the ship on Thursday, packing into yellow buses and leaving for stations and airports. But questions are increasingly being asked as to the wisdom of allowing former Diamond Princess passengers to roam freely around Japan's crowded cities, even if they have tested negative.

The death of the two elderly passengers is likely to add to the criticism.

A specialist in infectious diseases at Kobe University slammed "completely chaotic" quarantine procedures onboard, in rare criticism from a Japanese official.

"The cruise ship was completely inadequate in terms of infection control," said Kentaro Iwata in videos he has since deleted.

Japan's health ministry insisted it had conducted "consultations on appropriate infection control in the ship" with experts and taken a range of measures.