China plans to toughen border controls on people arriving from South Korea, in apparent retaliation for Seoul's decision to extend visa restrictions on travelers from China.

The South Korean Embassy in Beijing said on its website on Tuesday that Chinese authorities notified it of its plan to mandate PCR tests for passengers on direct flights from South Korea upon arrival, starting Wednesday.

The notification comes as the South Korean government announced last Friday that it will extend its restrictions on issuing short-term visas to travelers from China due to the surge in coronavirus infections there. The measure will remain in place until the end of February.

Chinese Foreign Ministry Spokesperson Mao Ning on Tuesday accused "a handful of countries" of insistently "imposing discriminatory entry restrictions targeting China."

She said, "China firmly rejects this and has reason to take reciprocal measures as necessary."

On the same day, Prime Minister Han Duck-soo suggested that Seoul could lift the visa restrictions earlier than scheduled if the tally of infections among travelers from China proves to be manageable.