A state-backed business behind the development of a new orbital rocket has announced that work has been halted owing to the coronavirus outbreak in northern China.

According to Expace Technology, a subsidiary of the state-owned China Aerospace Science & Industry Corporation, every member of the testing team for the Kuaizhou 1A orbital launch rocket has been placed in an "emergency state of semi-lockdown."

"According to regulations from the Jiuquan satellite launch centre and the local government, work related to the fifth Kuaizhou 1A rocket has been suspended," the company said on its WeChat social media account on Tuesday.

The team is based in Jiuquan, Gansu's northwestern province, where COVID-19 cases were detected after visitors tested positive for the virus.

China's National Health Commission announced on Wednesday that 17 locally acquired symptomatic cases had been identified a day earlier, the majority of which were in the Inner Mongolia autonomous region and neighboring Gansu province.

In Gansu and Yunnan provinces, four asymptomatic community cases were also documented. Unless they show symptoms, they will not be added to the official tally.

Hotels have been reserved for the Kuaizhou 1A testing team, with meal hours set aside to prevent them from coming into contact with the general population. The team's volunteers have also organized mass testing and temperature inspections.

The newest COVID-19 outbreak in China spread across the country after a retired couple in their 60s visited Xian, the provincial capital of Shaanxi in northern China, as well as the Gansu cities of Zhangye, Jiuquan, and Jiayuguan. They also paid a visit to Ejin Banner in western Inner Mongolia, according to the Shaanxi health authority on Monday.

It's unknown how the pair, who worked as professors at a Shanghai institution before retiring, became infected. On Sunday, their traveling companions, two couples and another man, all in their 60s and from Shanghai, tested positive for the coronavirus and were treated in Xian.

Expace was founded to help China's commercial aerospace industry flourish by operating and developing rockets. Several Earth observation satellites have already been launched by the Kuaizhou 1A, a small solid-fuel carrier rocket.

The new Kuaizhou 1A rocket has been assembled and is awaiting flight. It is 20 meters (65 feet) in length and has a launch mass of 30 tons.