WRAPUP 10-People returning to Beijing under quarantine as China struggles to pick up economy

(Adds comment from top Chinese official)

* Those who refuse will be punished, state-backed daily says

* WHO mission heading to China this weekend

* China says mainland cases rise by 5,090, with 121 new deaths

* Cities, offices and factories still struggling with restrictions

* Cambodian PM welcomes passengers from cruise liner

* Graphics on the outbreak https://tmsnrt.rs/2GVwIyw

By Kevin Yao

BEIJING, Feb 14 (Reuters) - The Chinese capital Beijing on Friday imposed a 14-day self-quarantine on people returning to the city from holidays to prevent the spread of the new coronavirus, and threatened to punish those who failed to comply.

It was not immediately clear how the restriction, relayed by the official Beijing Daily newspaper, would be enforced, or whether it would apply to non-residents of Beijing or foreigners arriving from abroad.

A top Chinese official, in an interview with Reuters, acknowledged that coronavirus was a deep challenge, but defended Beijing's management of the epidemic and lashed out at the "overreaction" of some other countries.

State Councillor Wang Yi, who also serves as China's foreign minister, said China has taken the most rigorous and decisive measures to fight the epidemic, with many efforts going beyond international health regulations and World Health Organization (WHO) recommendations.

"Through our efforts the epidemic is overall under control," he said.

China is struggling to get its economy going after the annual Lunar New Year holiday, which was extended for 10 days to help contain the outbreak of the new and highly contagious respiratory virus.

Authorities reported 5,090 new cases in mainland China, including more than 120 deaths, taking the number of infected to 63,851, and the number of deaths to 1,380.

The figures give no sign that the outbreak is nearing a peak, said Adam Kamradt-Scott, an infectious diseases expert at the Centre for International Security Studies at the University of Sydney.

But with 500 million people already affected by movement and travel restrictions, President Xi Jinping warned top officials last week that efforts to contain the virus had gone too far and were threatening the economy, sources said.

In cities such as Beijing and the business hub Shanghai, streets and subways remain largely deserted with many shops and restaurants empty or shut.

Government employee Jin Yang, 28, made it to his Beijing office but found it "anything but normal."

Canteen lunches are banned in favour of boxed meals eaten at desks. Meetings are held online, not in person. Employees must wear masks all day and report their temperature twice a day as fever is one of the virus' main symptoms.

Outside mainland China, there have been nearly 450 cases in some 24 countries and territories, and three deaths. Japan confirmed its first coronavirus death on Thursday. One person has died in Hong Kong and one in the Philippines.

WUHAN'S SELF-HELP

Wuhan, the central Chinese city of 11 million people where the outbreak began, has been hardest hit by the virus.

With all public transport, taxis and ride-hailing services shut down in the city, volunteer drivers are responding to requests on ad hoc messaging groups to ferry medical staff and others in vital jobs to and from work, risking their own health.

Others work round the clock to find accommodation for medical workers in hotels that have volunteered rooms.

"Everyone in our group has such a strong sense of mission," said 53-year-old Chen Hui, who runs one of the ad hoc ride services.

The virus is killing around 2% of those infected, but has spread faster than other respiratory viruses that have emerged this century.

"From now on, all those who have returned to Beijing should stay at home or submit to group observation for 14 days after arriving," read the notice from Beijing's virus prevention working group cited by the Beijing Daily.

"Those who refuse to accept home or centralised observation and other prevention and control measures will be held accountable under law," it said.

A WHO-led joint mission with China will start its outbreak investigation work this weekend, focusing on how the new coronavirus is spreading and its severity, its chief Tedros Adhanom Ghebreyesus said.

The mission will also seek more details on how, where and when the more than 1,700 healthworkers infected contracted the new virus, WHO officials said.

SLOWDOWN

Economists polled by Reuters said China's economic downturn would be short-lived if the outbreak was contained, but expected this quarter would show China's slowest growth rate since the global financial crisis.

The Chinese carmakers' association said auto sales in China were likely to slide more than 10% in the first half of the year because of the epidemic.

Vietnam has imposed a 20-day quarantine on Son Loi, a rural community outside Hanoi where 11 of the country's 16 coronavirus cases are located, two local officials said.

The virus is taking its toll on the $46 billion global ocean cruise industry.

The biggest cluster of infections outside China has been on a cruise liner quarantined in a Japanese port, with 218 people on board confirmed as infected and taken to hospital.

On Friday, some passengers were allowed to disembark to complete their quarantine on shore.

(Reporting by Yilei Sun, Huizhong Wu, Vincent Lee, Brenda Goh, Gabriel Crossley, Kevin Yao, Cheng Leng and David Stanway in Beijing; Prak Chan Thul in Sihanoukville; Hideyuki Sano in Tokyo; Colin Packham and Paulina Duran in Sydney; Uday Sampath in Bengaluru; Ryan Woo and Alessandra Galloni in Berlin; Writing by Lincoln Feast and Kevin Liffey Editing by Philippa Fletcher, Timothy Heritage and Bill Bekrot)