BEIJING-At least 10 people on board a cruise ship docked in the Japanese port of Yokohama have tested positive for coronavirus, health authorities say.

Almost 300 of the 3,700 people on the Diamond Princess have been tested so far. The number of infected could rise.

The checks began after an 80-year-old Hong Kong man who had been on the ship last month fell ill with the virus.

Some 3,600 people on a second cruise ship docked in Hong Kong are also being tested.

Chinese health authorities are stepping up efforts to control the spread of the virus, with approximately 18 million people in the east of the country now required to stay at home.

In Wuhan, the epicentre of the virus, 11 large public venues including sports arenas are being turned into makeshift hospitals to provide an additional 10,000 beds for the sick. Two new hospitals have already been built there since the outbreak started.

President Xi Jinping said China’s preventive measures were “achieving a positive effect”, state media reported. He said China was confident and capable of winning the war against the virus, after authorities were criticised for their initial handling of the outbreak.

The WHO has declared a global health emergency over the outbreak but said it did not yet constitute a “pandemic”, or the worldwide spread of a new disease.

However, the number of cases in China jumped by nearly 4,000 on Tuesday alone to more than 24,300, with another 65 deaths bringing the total to 490.

The new coronavirus causes severe acute respiratory infection and symptoms usually start with a fever, followed by a dry cough. Most people infected are likely to fully recover - just as they would from a flu.

In other developments:

The Philippines confirms its third case of the virus, and Australia its 13th. South Korea has two new confirmed cases

Hong Kong imposes compulsory quarantine on all visitors from mainland China. Health workers in the territory are on strike, demanding the complete closure of the border

The Hong Kong flagship airline Cathay Pacific asks its staff to take three weeks’ unpaid leave

Organisers of the 2020 Tokyo Olympics say they are “seriously concerned” about the spread of the virus and its possible impact on the games

How did the virus get on board the ship?

There is a much smaller number of cases in countries around the globe other than China - two people outside of mainland China have died of the disease.