BEIJING, April 30 (Xinhua) -- The number of existing imported cases of the novel coronavirus disease (COVID-19) on the Chinese mainland was 525 as of the end of Wednesday, the lowest in 35 days, a health official said Thursday.

Mi Feng, a spokesperson for the National Health Commission (NHC), made the remarks at a press conference.

Nearly two-thirds of the Chinese mainland's imported COVID-19 cases had been cured and discharged from hospitals, he said. As of the end of Wednesday, the Chinese mainland had reported a total of 1,664 imported cases, showed NHC figures.

"However, the growth trend of the epidemic abroad continues, and the complexity of preventing infection resurgence at home is also increasing," Mi said.

Nearly 30 percent of the Chinese mainland's existing locally-transmitted cases are severe cases, he noted, saying all-out efforts should be made to treat patients with the help of experts.

The number of the Chinese mainland's existing COVID-19 cases, including the imported, was 619 as of the end of Wednesday, according to the NHC.