Seven passengers from a flu-infected flight were put under quarantine in China on Saturday, the Chinese Health Ministry said.

Three Japanese passengers boarding the U.S. airlines NW025, which flew from Canada to Japan via the United States on Friday, had been diagnosed with influenza A/H1N1, the ministry said, citing a Saturday notification from the World Health Organization China office.

Of the co-passengers, some had left Japan, including seven who arrived in Chinese cities of Shanghai and Beijing Friday night.

The ministry said it then immediately told relevant local health departments to track down the seven passengers.

So far they had all been located and put under medical observation, the ministry said in a statement.

Previously, China had quarantined 166 passengers who were on board flight AM098 (Mexico City-Shanghai) on April 30 after a Mexican, one of the travelers, was later confirmed in Hong Kong to have influenza A/H1N1.

Among them, 38 Mexican passengers and crew were flown back to Mexico on Monday. And the remaining 128 passengers, including a few Mexican nationals, continued their week-long quarantine across China till Thursday, when they were released after showing no flu-like symptoms or tested negative to the virus.

As of 8 a.m. Saturday, no confirmed or suspected A/H1N1 cases had been reported on the Chinese mainland, the ministry said.

Worldwide, 2,500 confirmed cases, including 46 fatalities, had been reported in 25 countries and regions by then.

(Xinhua News Agency May 10, 2009)