The World Health Organisation chief on Monday warned countries to prepare for a "potential pandemic" of new coronavirus, calling the sudden increase in cases in Iran, Italy and South Korea "deeply concerning".
But Tedros Adhanom Ghebreyesus also said a WHO joint mission to China that ended on Monday found the virus there "peaked" between January 23 and February 2 "and has been declining steadily since then".
"This virus can be contained," Mr Tedros said. "Indeed there are many countries that have done exactly that."
He said China's measures to lock down several cities helped to prevent an even bigger spread.
China has reported a total of 77,362 cases of Covid-19 and 2,618 deaths. Outside China there are now 2,074 reported cases in 28 countries and 23 deaths, WHO figures show.
The organisation has declared it a global health emergency but has stopped short of calling it a pandemic.
"For the moment we are not witnessing the uncontained global spread of this virus and we are not witnessing large-scale deaths," Mr Tedros said in Geneva.
He said, however, that countries should be doing everything to prepare for a potential pandemic.
"What we see are epidemics in different parts of the world affecting countries in different ways and requiring a tailored response," Mr Tedros said.
Michael Ryan, head of the WHO's health emergencies programme, said a team had arrived in Italy on Monday and another was expected in Iran on Tuesday.
Mr Ryan cautioned over the apparently high mortality rate in Iran, where the government has reported 64 infections and 12 deaths.
"We may only be detecting severe cases," he said. "The virus may have been there longer than we had previously suspected."
Mr Ryan said transmission might have occurred through events such as religious festivals.
Mr Tedros on Monday evening met UN Secretary General Antonio Guterres.
Mr Guterres warned that all countries must do their utmost to prepare for a spread of the disease.
“It is still possible for this disease to be contained," he said.
"But if some countries fail, some do not do everything that is needed, this can still become out of control with dramatic consequences on global health and global economy.
"So, my strong appeal is for all countries to assume their responsibilities and know that they can fully count on the WHO to support them in that effort.”
South Korea has had a rapid rise in infections since it appeared in a religious sect in Daegu last week.
The country reported more than 200 infections and two more deaths on Monday, bringing the total number of cases to more than 830, by far the most outside China.
Eight people have died from the virus there, and President Moon Jae-in over the weekend raised the country's virus alert to the highest "red" level.
As part of containment attempts, school holidays were extended nationally while the 2.5 million people of Daegu were told to remain indoors.
Authorities in Hong Kong announced that from Tuesday it would not allow arrivals from South Korea, other than returning residents.
Mongolia earlier announced it would not allow flights from South Korea to land.
In Geneva, South Korean Foreign Minister Kang Kyung-hwa warned governments against "taking action that would fan public panic".
"I am deeply concerned at incidents of xenophobia and hatred, discriminatory immigration controls and arbitrary repatriation," Ms Kang said.
Fears were also growing in Europe, with Italy reporting two more deaths on Monday, bringing the total to five.
The WHO declared the 2009 H1N1 swine flu outbreak a pandemic, which turned out to be mild, leading to some criticism after pharmaceutical companies rushed development of vaccines and drugs.
WHO declared the novel coronavirus that emerged in Wuhan, China, in December a public health emergency of international concern on January 30.
The designation, which remains in place, was aimed at helping countries with weaker health systems to shore up their defences, especially in Africa.
Stock markets around the world witnessed sharp falls
Oil prices dropped to their lowest in two weeks in early trading as stock markets around the world had sharp falls, weighed down by concerns about the rapid spread of the coronavirus.
Brent, the most widely used pricing benchmark, fell 4.6 per cent and was trading at $55.92 a barrel at 6.10pm UAE time on Monday, while West Texas Intermediate slid 4.8 per cent at $50.92 a barrel.
Markets around the world also fell as the epidemic risked turning into a pandemic.
In the US, the Dow Jones Industrial Average opened 2.8 per cent lower, the S&P 500 was 2.6 per cent down and the Nasdaq composite index traded 3 per cent lower shortly after the market opened.
Middle East countries confirm first cases
Health ministries in Oman, Bahrain, Kuwait, Iraq and Afghanistan confirmed their first cases of the coronavirus on Monday.
A Bahraini national showed symptoms after arriving on a flight from Iran and was transferred to the Ebrahim Khalil Kanoo Medical Centre for immediate testing, treatment and isolation, the country's Ministry of Health said in a statement.
Afghanistan also confirmed its first case of coronavirus in western Herat province.
"The ministry calls upon all citizens and residents who are experiencing symptoms of Covid-19, including a fever, coughing and difficulty breathing, or those who have travelled to one of the countries infected with the disease or have interacted with a person travelling from any of those locations, or interacted with an infected patient, to isolate themselves," the ministry said.
The Omani Health Ministry said two women who recently had the disease diagnosed had recently visited Iran.
Kuwait has reported that three people, who had travelled to Iran, have tested positive for coronavirus.
The country's state news agency said the cases, which included a Saudi national, were among 700 people moved from the Iranian city of Mashad last week.
On Monday, Kuwait's government abruptly cancelled all celebrations to mark the country’s National Day on Tuesday. It also banned all sports fixtures for two weeks.
Bahrain civil aviation authority on Monday suspended all its flights from Dubai airport and Sharjah airport for 48 hours over coronavirus fears.
There are at least 15 flights a day to Bahrain from Dubai International, being the region's main aviation hub.
Iran travel bans and border closures
On Monday, the UAE announced that Emiratis were banned from travelling to Iran and Thailand. Oman said it was halting flights to Iran.
Iraq said it had closed its Safwan border crossing with Kuwait amid fears of the virus spreading.
Last week, Kuwait began bringing back 750 nationals from Iran, where the death toll from coronavirus rose on Monday to 12, with 47 now infected, Health Minister Saeed Namaki said.
The outbreak in Iran centred mostly on the city of Qom but spread rapidly in recent days to at least four other cities.
Iranians went to the polls on Friday with many wearing masks to ward off infection and authorities have begun daily sanitisation of the metro in Iran's capital, Tehran.
Turkey and Pakistan are among seven countries that have now closed their borders with Iran over the coronavirus outbreak.
Parts of the country are in lockdown, with schools, universities, cinemas and theatres closed in 13 Iranian provinces.
Lebanon announced its first case of coronavirus after a woman tested positive following a flight from Qom on Thursday.
Lebanese expressed their anger on social media channels over the country's refusal to cancel flights from Iran.