Fears mounted Saturday over the rise of new cases and fatalities outside China from the new coronavirus outbreak, as the World Health Organization warned of a shrinking window to stem the spread of the deadly disease.

The warning came as the first European died from the new COVID-19 strain, which first emerged in December in central China but has now spread to over 25 countries and caused more than a dozen deaths outside the country.

A 78-year old Italian man died after testing positive for the virus, with the death toll reaching four in Iran, and a number of cases reported across the Middle East, including the first infections in Israel and Lebanon.

A second person died in South Korea, authorities reported Saturday, as the number of cases in the country spiked.

Italy has locked down ten towns and asked over 50,000 people to stay home -- a move with echoes of China's lockdown of entire cities in Hubei province at the centre of the outbreak.

In China, the number of cases outside Hubei, where millions remain under quarantine, has been generally declining, although new hotspots were found in several prisons and hospitals Friday. But just 31 new cases were reported outside the central province Saturday, as the national number of cases rose past 76,000.

The outbreak has now claimed 2,345 lives in China.

Concerns have also risen about the reliability of the official data, however, after Hubei officials changed methods of counting cases and amended their figures again. 

A WHO-led team of experts are set to visit Wuhan, the capital of the province, on Saturday.

Meanwhile WHO chief Tedros Adhanom Ghebreyesus warned that the "window of opportunity" to contain the international spread of the outbreak was "narrowing", as cases surged across the Middle East and in South Korea.

He warned that if countries did not quickly mobilise to fight the spread of the virus, "this outbreak could go in any direction. It could even be messy."

- International spread -

Cases of the deadly virus were reported in a range of countries in the Middle East on Friday, with the first cases in Israel and Lebanon.

Iran said four people there had died and 18 been infected from the outbreak. Iraq and Kuwait, which share borders with Iran, were on high alert for a potential outbreak after banning travel to and from the Islamic republic, although they have not confirmed any cases domestically.

Nearly 350 people have been infected in South Korea, including two deaths, making it the hardest-hit country outside China.

The US advised citizens to avoid travelling by cruise liner in Asia because it said the vessels acted as amplifiers of the virus.

Several Australians and an Israeli evacuated earlier this week from the stricken Diamond Princess cruise ship tested positive for coronavirus on returning to their home countries. They were previously cleared in Japan.

The cases will fuel questions about Tokyo's policy of allowing former passengers to return home after testing negative. Two former passengers, both Japanese and in their 80s, died in Japan on Thursday.

The British government confirmed on Twitter that an evacuation flight left Japan Saturday, with 32 British and European passengers on board.

pic organisers on Saturday postponed training for their army of volunteers due to the coronavirus outbreak, but said that there was "no consideration" of cancelling the Games.

- 'Critical moment' -

Nearly 400 new cases were reported nationwide in China on Saturday, less than half the number of new cases the previous day.

The drop in new cases of the novel coronavirus came as officials in Hubei province were ordered to revise figures to clear "doubt" around the data.

Officials retroactively revised upwards previously reported data for two days in the last week -- the latest in a string of amendments to the figures officially reported at the epicentre.

Several changes in Hubei's counting method has further complicated efforts to track the spread of the illness.

China has said the slowing cases are evidence that its drastic containment measures are working -- but fresh infections emerged at two Beijing hospitals, and more than 500 others were reported in prisons across the country.

In a letter to the Bill & Melinda Gates Foundation thanking the organisation for its financial support, Chinese President Xi Jinping said China was at a "critical moment" in the fight against the outbreak. Xi said the "unprecedented measures" were "delivering substantial results".

Many nations have banned travellers from China and airlines have suspended flights to and from the country.