The new COVID-19 cluster reported on Wednesday in Beijing has involved a wider range of areas and more people with rapid spread, which has added difficulties to the capital's epidemic control and prevention, a senior official said on Thursday afternoon.

"Beijing has taken action immediately once it learned of a confirmed case who had traveled to Beijing from Jilin province," Xu Hejian, spokesperson of the Beijing government, said at a news conference on Thursday.

The authority started mass nucleic acid testing for all close contacts of the confirmed case, who came to Beijing for an oil industrial conference late Wednesday night.

Beijing reported six locally transmitted cases and one asymptomatic case on Thursday. Many of them are employees of PetroChina Co who went to the same oil conference.

One of the employees lives in a residential community in Haidian district, and all her family members including her husband, daughter, mother-in-law and father-in-law were infected.

To cut infection risks, Beijing will strengthen the management of conferences, and has stated ones which can be held online should not be held in-person. If it's absolutely necessary, attendees of conferences in Beijing should not go out to eat in order to reduce infection risks.