BEIJING - At least 113 people, who were on the same flight with a Mexican national later diagnosed with swine flu in Hong Kong, have been quarantined in China to test whether they are infected with the H1N1 virus, health officials here said.

However, none of them have displayed any flu symptoms so far, according to the officials.

The Mexican, a 25-year-old male, arrived in Shanghai Thursday aboard flight Aeromexico 098, which carried 176 people and 13 crew members.

Of the passengers, 56 disembarked in Shanghai, 41 caught a connecting flight to Guangzhou, 17 left for Beijing and two were refused entry to China.

That accounts for 116 of the passengers, some of whom - including the infected Mexican - flew on to Hong Kong through a connecting flight.

Wu Fan, chief of Shanghai Municipal Centre for Disease Control and Prevention, said all of the 48 passengers whose destination was Shanghai were found. They are kept in a hotel for a week-long medical observation. Family members of these passengers were also told to maintain health observation at home.

The entire crew remained in Shanghai and were put into quarantine, Wu confirmed.

The health authorities in Shanghai are still looking for eight other passengers who also disembarked in Shanghai but only stayed for a short period of time.

Of the 17 who flew to Beijing, two left the city for Hebei and Jiangsu provinces and were put into quarantine by local disease control and prevention centres.

The 15 whose final destination was Beijing were admitted by Beijing Ditan Hospital, Cheng Jun, deputy head of the hospital, told reporters Saturday.

The health authorities of south China’s Guangdong province said they had only found 30 of the 41 passengers who caught a connecting flight to Guangzhou together with the Mexican patient. They are seeking the remaining 11 people.

East China’s Zhejiang and Jiangsu provincial authorities have also found 16 passengers who took the same flight with the Mexican national. These passengers were all quarantined.

Five more people were also put in observation in Jiangsu province, taking the number of people quarantied to 113, the health officials added.

The Mexican became Hong Kong’s first confirmed case of influenza A/H1N1 infection Friday, prompting authorities to immediately raise the flu alert level from serious to the highest level of emergency.