BEIJING-- China resumed mandatory COVID-19 tests for arrivals from South Korea only Wednesday, in its latest tit-for-tat response over Seoul's strengthened antivirus curbs against travelers from the neighboring nation.

In a notice sent Tuesday to airlines operating between the two neighbors, Chinese aviation authorities said all passengers on board direct flights from South Korea to China will receive polymerase chain reaction tests on arrival from Wednesday, according to the officials and sources. Those who test positive are required to be quarantined or hospitalized.

It is the latest in a series of retaliatory measures targeting South Korea after Seoul tightened curbs on travelers from China last month due to the fast spread of new cases in the neighboring country.

Last month, China scrapped its previous requirement of mandatory polymerase chain reaction tests on all international arrivals. Seoul's embassy in Beijing said it was informed by the Chinese government of the new regulation for travelers from South Korea only.

Chinese Foreign Ministry Spokesperson Mao Ning said in a regular press briefing Tuesday there needs to be corresponding and "equivalent measures," voicing concerns over what it called Seoul's "discriminatory" entry restrictions.

A Seoul foreign ministry official said China should not restrict people's entry across its border for reasons other than those of pandemic response measures. (Yonhap)