Passengers arriving from China enters a COVID-19 testing center at the Incheon International Airport in Incheon, South Korea, Tuesday, Jan. 10, 2023. AP
A brief notice posted online by the Chinese Embassy in Seoul said the ban would apply until South Korea lifted its "discriminatory measures on entrance by China'' to the country.
No other details were given, although China has threated to retaliate against countries that require travelers from China to show a negative test result for COVID-19 taken within the previous 48 hours.
China requires the same measures for arriving travelers. Around a dozen countries have followed the U.S. in requiring negative tests for travelers coming from China, which has lifted most of its "zero-COVID'' restrictions for the first time in three years but also has been experiencing a major outbreak since last month.
The World Health Organization and several nations have accused China of withholding data on its outbreak. The testing requirements are aimed at identifying potential virus variants carried by travelers.
China's ambassador to Australia said the response of those nations to China's COVID-19 outbreak hadn't been proportionate or constructive.
Xiao Qian told reporters in Canberra that China had shifted its strategy late last year from preventing infections to preventing severe cases. He said countries should use a science-based response.
"Entry restrictions, if they're targeted at China, they're unnecessary,'' the ambassador told reporters.
"If you look at some other countries in the world and their policies toward China, I mean, their responsible measures toward China (are) not constructive. It's not based on science. It's not proportionate,'' he said.
The online notice at the embassy in Seoul did not say why China singled out South Korea for retaliation, although president and Communist Party leader Xi Jinping's deeply nationalistic government has long resented Seoul's alliance with the U.S.
The once-cordial ties between South Korea and its biggest trading partner soured after China targeted businesses, sports teams and even K-pop groups to protest deployment of an advanced U.S. anti-missile system in South Korea. China fought on the side of North Korea in the 1950-1953 war and has remained a staunch supporter of Pyongyang amid its missile launches and nuclear tests.
China abruptly reversed its strict pandemic containment requirements last month in response to what it says was the changing nature of the outbreak. That came after three years of lockdowns, quarantines and mass testing that prompted protests on the street in Beijing and other major cities not seen in three decades.
The most optimistic forecasts say China's business and consumer activity might revive as early as the first quarter of this year. But before that happens, entrepreneurs and families face a painful squeeze from a surge in virus cases that has left employers without enough healthy workers and kept wary customers away from shopping malls, restaurants, hair salons and gyms.
The abrupt decision by Xi's government to end controls that shut down factories and kept millions of people at home will move up the timeline for economic recovery, but might disrupt activity this year as businesses scramble to adapt, forecasters say.
China is now facing a surge in cases and hospitalizations in major cities and is bracing for a further spread into less developed areas with the start of the Lunar New Year travel rush, set to get underway in coming days. While international flights are still reduced, authorities say they expect domestic rail and air journeys will double over the same period last year, bringing overall numbers close to those of the 2019 holiday period before the pandemic hit.