Chief Executive Donald Tsang says Hong Kong's response level has been raised from "serious" to "emergency" as a confirmed case of Influenza A (H1N1) - previously known as "swine flu" - has been found in the city.

Speaking to reporters tonight, Mr Tsang said the 25-year-old Mexican man travelled from Mexico to Hong Kong through Shanghai yesterday. The patient developed symptoms hours after his arrival in the city and sought medical treatment at Ruttonjee Hospital.

An emergency ward doctor suspected the man may have had the virus, and immediately sent him to an isolation ward. Initial test results indicated it was a suspected Influenza A (H1N1) case. Further investigations by the University of Hong Kong confirmed it as the city's first case at 8pm tonight.

The patient, who did not develop a fever until the middle of the night, is stable. Two of his travel companions, and a local person who contacted him, have also been admitted to Princess Margaret Hospital's isolation ward, along with the Mexican man. His contacts do not have any symptoms.

The Chief Executive will chair a steering committee to determine ways to stem the virus's spread, and he urged the public not to panic.

Noting normal public activities such as school classes and economic activities can continue as usual, he urged people to enhance measures to guard against the virus.

Patient contacts urged to come forward

The 173-room Metropark Hotel in Wan Chai where the patient had stayed before seeking treatment has been quarantined. His was room 1103.

The Centre for Health Protection is urging Metropark Hotel staff and guests, and passengers of China Eastern Airlines flight MU505 that arrived in Hong Kong from Shanghai at 12:49pm yesterday, to call its hotline, 2125 1111.

With the co-operation of the hotel and the airline, the centre is tracing all 200-plus hotel guests, 100 or so hotel staff, and the 140-plus passengers and crew onboard the flight.

It is also tracing two taxi drivers: one who took the man from the airport to the hotel, and one who drove the man from the hotel to Ruttonjee Hospital last night.

Anyone who had come into contact with the patient - including passengers who sat in the three rows directly in front and the three directly behind seat 23A, where he sat - and hotel staff and guests, will be quarantined for seven days.

Appeal to contacts

At a press briefing that began after 9pm today, Secretary for Food & Health Dr York Chow appealed to these people to come forward.

"If you are watching, listening, I hope you understand that we all care for your health and the possibility of you spreading the swine flu to your family, your friends and other residents of the hotel. We know this is an inconvenience to you, but if you co-operate and look after yourself well, you will not catch the virus, and stay healthy. We will try to give as much supprt to you as possible so you can maintain your health," he said.

For the safety and health of all people, he stressed, he hoped they would understand.

Holiday camps to serve as isolation centres

The Leisure & Cultural Services Department has evacuated guests at the Lady Maclehose holiday camp in Sai Kung and Lei Yue Muen holiday camp in Chai Wan and is readying the facilities to serve as isolation centres, if required, by tomorrow.

Dr Chow said, as this is the first case in Hong Kong, "we must be very careful. The chance of controlling and containing this disease is limited, so we will be draconian in our policy. We don't know how damaging or virulent this will be. We don't want it to spread in our community - or globally."

Hong Kong officials have alerted the World Health Organisation, the Shanghai municipality health bureau and the Mexican Consul-General to the case.

Anyone who flew on AeroMexico flight AM98 from Tijuana to Shanghai on April 29 is also urged to call the hotline, 2125 1111.