BEIJING, Feb. 27 -- China's customs authorities have found 30 types of imported COVID-19 variants, including the first cases of XBB.1.9, XBB.1.9.1, and XBL, since China removed certain COVID-19 restrictions on international passenger flights on Jan. 8, an official said Monday.

To prevent imported cases, the customs will follow the situation and improve monitoring and alarming, said Li Zhengliang, an official with the General Administration of Customs, at a press conference.

The customs will strengthen COVID-19 prevention and control at ports of entry and guard against imports of other viruses at the same time, he said.

As the pandemic is still ongoing and the virus is still mutating, China faces increasing challenges in guarding against imported COVID-19 variants and other infectious diseases, he said.

The customs will work with the health authorities to closely monitor imported COVID-19 variants, as well as the global pandemic and virus mutation, Li said.