A 60-year-old US citizen diagnosed with the Coronavirus died on Thursday (7) in Wuhan, the city at the epicentre of the health emergency, according to the US embassy.
However, it did not provide more details about the person.
A Japanese man in his 60s with a suspected coronavirus infection also died in hospital in Wuhan, the Japanese foreign ministry said. It added that it was difficult to confirm if he had the illness.
The only fatalities so far, outside mainland China, were a Chinese man in the Philippines and a 39-year-old man in Hong Kong.
Currently, more than 320 cases have emerged in nearly 30 other countries.
Nearly 35,000 people have been infected by the new strain, which is believed to have emerged in a market selling wild animals in Wuhan last year before spreading across China.
The death toll from the coronavirus outbreak soared to 722 on Saturday (8). As many as 86 more people died in mainland China — the highest one-day jump so far.
The coronavirus death toll was closing in on the 774 killed worldwide during the SARS epidemic in 2002.
Hong Kong imposed a mandatory quarantine on mainland arrivals to block the spread of an epidemic.
The US health department is working with pharmaceutical firm Regeneron to develop a treatment using a class of drug that has boosted survival rates among Ebola patients.
Earlier, Chinese doctors confirmed they had been giving anti-HIV drugs to coronavirus patients in Beijing, based on a 2004 study published after the SARS outbreak that showed positive responses.