Chinese authorities on Monday slightly relaxed their month-long quarantine measures in Wuhan, allowing some people to leave the epicentre of the country's virus epidemic under certain conditions.

The city of 11 million has been under lockdown since January 23 after authorities shut down transport links into and out of the city in an effort to contain the new coronavirus outbreak.

The decision comes as the official number of new cases has been in the hundreds for the past five days, after being in quadruple digits every day for weeks.

Non-residents may leave the central city of 11 million people if they show no symptoms of the new coronavirus and have never had contact with patients, the city said in a statement.

People with special reasons to leave the city including those who need treatment for other medical conditions and those doing epidemic prevention work may also leave Wuhan, the statement said.

Departures must be staggered and people must apply for permission from local authorities before leaving.

Cars leaving the city must not carry more than two people, including the driver, at a time, the city said, without mentioning whether air and rail transport would be resumed.

Once travellers have reached their destinations outside of Wuhan, they must report themselves to local authorities and monitor their health for 14 days, the city said.

People may also enter the city for epidemic prevention or other production-related reasons or if they are Wuhan residents who have previously been unable to return home.

Hundreds of foreign nationals have been airlifted from Wuhan back to their countries by several governments including the United States, France and Britain.

The COVID-19 disease has killed nearly 2,600 people and infected some 77,000 in China.

The epidemic's spread has slowed down in China outside of Hubei province, of which Wuhan is the capital, while multiple other provinces have reported zero new infections for several days in a row.

All but 11 of China's 409 new cases Monday were reported in Hubei.

Wuhan, where the virus is believed to have originated late last year, continues to account for the majority of new cases and deaths in the country.

Wuhan on Monday reported 348 new virus cases, while five cities and the Shennongjia Forestry District in Hubei reported no new cases.

Experts from the World Health Organization visited Wuhan over the weekend.

They also met with Ma Xiaowei, the director of China's national health commission, and top officials at the centre for disease control for Hubei province, of which Wuhan is the capital.