China has reported 328 locally-transmitted COVID-19 cases this month, close to the total number of cases in the past five months, Mi Feng, spokesman for the National Health Commission, said on Saturday.

Fourteen provincial regions have reported locally-transmitted, confirmed or asymptomatic cases, he said.

The Joint Prevention and Control Mechanism of the State Council has sent work groups led by the commission and the National Administration of Disease Prevention and Control to Nanjing in East China's Jiangsu province and Zhang Jiajie in Central China's Hunan province to guide local epidemic containment and medical treatment of patients, he said at a news conference.

The Delta variant has become the dominant strain of novel coronavirus transmitted in the country and poses a bigger challenge in epidemic control efforts, Mi said.

The country also faces increasing pressure to prevent imported cases, with the number of daily imported cases in July reaching 27, as the pandemic still rages globally, he added.