Beijing announced Wednesday that people landing in the Chinese capital from countries hit by the new coronavirus epidemic will have to go into 14-day self-quarantine.
A day earlier, more than 250 people arriving in eastern China from South Korea were placed in isolation after passengers on two flights were discovered to have fevers.
Beijing had already ordered people returning to the capital to go into self-quarantine following the Lunar New Year holiday but exempted those arriving from abroad.
With the deadly virus now hitting countries in Europe, the Middle East and Asia, Beijing's health commission spokesman Gao Xiaojun told reporters on Wednesday that people arriving "from areas with severe epidemic situations abroad ... must accept home or concentrated medical observation for 14 days".
The eastern city of Qingdao and Dalian in the northeast announced similar measures.
Separately, the foreign ministry said China was "exploring the possibility" of adopting "scientific, appropriate, and targeted prevention and control measures" for people arriving from abroad.
Beijing has criticised countries for imposing bans on arrivals from China over the epidemic, which has killed more than 2,700 people and infected 78,000.
Five people travelling from Incheon in South Korea were found to have fevers after landing at Weihai in eastern Shandong province Tuesday and were immediately sent to a hospital for treatment and observation, state media said.
The remaining 158 passengers on the Jeju Air flight, which included South Korean, U.S., Ukrainian and Chinese nationals, were taken to a hotel for medical observation, CCTV said, without specifying the nationality of the five patients.
Another three travellers with fevers, all Chinese, arrived in the eastern city of Nanjing on Tuesday morning and were discovered to have symptoms after customs personnel boarded the aircraft on landing to screen passengers.
The three were immediately sent by ambulance to a hospital for isolation and testing, while 94 passengers were sent to a hotel to be quarantined, CCTV said.
None of the three people with fevers on the flight to Nanjing had any history of travel to Wuhan, the central Chinese city where the outbreak originated.
On Wednesday Chinese state media reported a case of "imported" coronavirus in the northwestern Ningxia region in a patient who travelled from Iran.
The People's Daily newspaper said the patient travelled from Tehran to the city of Zhongwei via Moscow, Shanghai and Lanzhou, in neighbouring Gansu province. The report listed all the forms of transport the patient had taken and urged anyone who took the same vehicles to get in touch with authorities.
Iran has reported 19 deaths and 139 cases of the virus.
The largest number of cases outside China is in South Korea, which has recorded 12 deaths and more than 1,200 infections.
Japan has reported at least 165 infections, in addition to an outbreak on the Diamond Princess cruise ship that was quarantined for weeks off Japan before 970 people were allowed to disembark last week.
Mongolia, which has closed its borders with China, announced it was banning flights to and from Japan and South Korea until March 11.