Hong Kong (CNN) The death toll from the novel coronavirus passed 2,000 on Wednesday, marking a grim milestone in the battle to contain the deadly outbreak, as countries across Asia registered an uptick in confirmed cases.

More than 74,000 people have now been infected by the virus in mainland China, with more than 1,000 other cases detected in 28 countries and regions.

On Wednesday morning, China reported an additional 136 deaths, bringing the total number of deaths there to 2,004, and the global death toll to 2,010.

There are now six deaths from Covid-19, the disease caused by the virus, outside mainland China. Hong Kong reported that a second person had died in the semi-autonomous territory, according to local health authorities. The victim is a 70-year-old man who was diagnosed on February 14.

Though the vast majority of deaths continue to be centered in China, concern is growing over expanding outbreaks in Singapore, Japan, South Korea and Hong Kong.

On Wednesday, the South Korean Centers for Disease Control and Prevention announced 15 additional cases, bringing the total number to 46 -- an increase of almost 50% in one day. Singapore has at least 81 cases and Japan has 68 cases and one death, not including the more than 500 cases aboard the virus-stricken cruise ship docked in the Japanese city of Yokohama.

Amid the sudden spike in numbers, Japan's health ministry has issued guidelines for people experiencing symptoms similar to the coronavirus in an effort to to prevent worried citizens from inundating hospitals by providing them with specific hotlines to call.

China praises virus response

In China, promising signs have emerged of a potential leveling off in the rate of infection. Outside of Hubei, the province at the epicenter of the outbreak, the number of new cases dropped for the 15th consecutive day, according to the country's National Health Commission.

Chinese President Xi Jinping said in a phone call with British Prime Minister Boris Johnson on Tuesday that China's measures to prevent and control the epidemic "are achieving visible progress," according to state news Xinhua

Xi said, "the battle has reached a crucial time" and China had "mobilized the entire country, and adopted the most comprehensive, rigorous and thorough prevention and control measures," Xinhua reported.

"Thanks to those arduous efforts, the situation is witnessing positive changes," Xi said.

Headlines across Chinese state media on Wednesday morning were full of positivity, touting China's ability to get on top of the virus's spread. One commentary in Xinhua said the fight against coronavirus would "not stop China's march towards rejuvenation."

Meanwhile, Hu Xijin, editor in chief of the state media outlet Global Times, tweeted that the country was on its way to victory.

"Daily new infection cases outside Hubei fell below 100 for the first time according to data released on Tuesday. We are on the way to the victory," tweeted Hu

But experts have warned that it is too soon to tell whether the virus is under control.

"This trend must be interpreted very cautiously. Trends can change as new populations are affected. It's too early to tell if this reported decline will continue. Every scenario is still on the table," Tedros Adhanom Ghebreyesus, director-general of the World Health Organization (WHO), said at a press conference Monday.

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Stringent and often draconian measures are also being ramped up in much of the country. CNN analysis found that on Chinese government orders, some 780 million people are still living under some form of restrictive movement, including all of Hubei, the northeastern province of Liaoning, and China's two most important cities, Beijing and Shanghai.

It comes as authorities make an effort to return to something like normality in many major cities and commercial hubs, with the long break forced by the outbreak taking its toll on the country's economy.

On Tuesday, Liu Zhiming, director of the Wuchang hospital in Wuhan, the city at the center of the outbreak, himself died of the virus, according to a statement released by local government authorities.

Liu was a neurosurgeon and the most senior health worker known to have died as a result of the coronavirus epidemic. His death could renew criticism that the government has not done enough to protect frontline medical workers, many of whom are overworked and overstretched.

Passengers start leaving Diamond Princess

A passenger of the Diamond Princess leaves Daikoku Pier on February 19 in Yokohama, Japan.

Outside of mainland China, the worst single outbreak has been on board the Diamond Princess cruise ship, under tight quarantine for two weeks in the Japanese port of Yokohama, south of Tokyo. More than 545 of the 3,600 people on board have tested positive for the virus so far. On Tuesday, 88 new cases were reported.

On Wednesday morning local time, passengers began to disembark from the ship after Japan's health ministry ended the quarantine period.

Questions have been raised, however, over the effectiveness of the isolation procedures onboard and whether disembarking passengers could pose a risk to the public as more test positive for coronavirus after leaving the ship.

The US Centers for Disease Control and Prevention (CDC) issued a statement criticizing the quarantine efforts taken on the Diamond Princess.

"While the quarantine potentially conferred a significant public health benefit in slowing transmission, CDC's assessment is that it may not have been sufficient to prevent transmission among individuals on the ship," the CDC said.

"CDC believes the rate of new infections on board, especially among those without symptoms, represents an ongoing risk," it continued.

All American passengers and crew will not be allowed to return to the US for at least 14 days after they leave the Diamond Princess, according to a US State Department spokesperson. There are more than 100 US citizens on board the ship or in hospitals in Japan.

Late Sunday, 328 American passengers were evacuated from the ship and are now in quarantine at two US bases. Of the 14 Americans who tested positive during final screenings, 13 are being treated at the University of Nebraska Medical Center and one patient who flew into Travis Air Force Base in Northern California, is currently under isolation at a Napa County medical center.

Australia, Hong Kong, Canada and the UK are also working to evacuated their citizens off the ship.

Separately, 781 passengers from the Westerdam cruise ship are one step closer to returning home after Cambodian health authorities said they had tested negative for coronavirus.

The Westerdam was refused entry from multiple ports before it was finally was able to berth in Cambodia on February 13. As of Tuesday, only 1,000 people were left on the ship, while another 500 or so were in Phnom Penh.

At the time, no cases of the virus had been reported aboard the ship. However, an 83-year-old American passenger tested positive for the virus in Malaysia while she was on transit home after disembarking.

The Cambodian government said the negative test results were from both passengers on the ship and in the city. Those still awaiting testing are not being held under any strict quarantine measures, Ministry of Health spokeswoman Dr. Or Vandline said.