Fears are growing that the coronavirus outbreak could reach pandemic scale as more cases emerge around the world.
Most infections are in China but other nations like South Korea, Italy and Iran are battling the virus, which causes respiratory disease Covid-19.
A pandemic is when an infectious disease spreads easily from person to person in many parts of the world.
Worldwide stock markets saw sharp falls because of concerns about the economic impact of the virus.
China said it would postpone the annual meeting of the National People's Congress next month, to "continue the efforts" against the coronavirus.
The body, which approves decisions made by the Communist Party, has met every year since 1978.
About 77,000 people in China, where the virus emerged last year, have been infected and nearly 2,600 have died.
More than 1,200 cases have been confirmed in about 30 other countries and there have been more than 20 deaths. Italy reported three more deaths on Monday, raising the total there to six.
The proportion of infected people who die from Covid-19 appears to be between 1% and 2%, although the World Health Organization (WHO) cautions that the mortality rate is not known yet.
On Monday Iraq, Afghanistan, Kuwait, Oman and Bahrain reported their first cases, all involving people who had come from Iran. Officials in Bahrain said the patient infected there was a school bus driver, and several schools had been closed as a result.
Among other developments:
WHO chief Tedros Adhanom Ghebreyesus warned on Friday that the window of opportunity to contain the virus was "narrowing".
Paul Hunter, professor of health protection at the University of East Anglia in the UK, echoed his fears, saying the spike in cases outside China was "extremely concerning".
"The tipping point after which [we lose] our ability to prevent a global pandemic seems a lot closer after the past 24 hours," he said on Monday.