Hong Kong  - Three more travellers on board a Japan-bound flight found to be carrying passengers with swine flu were quarantined and tested for the virus in Hong Kong Monday.

Two other passengers who got off the plane from Canada via the US in Hong Kong were already tested and cleared of the virus but placed into quarantine for one week.

They were among 400 passengers on board a Northwest Airlines jet that landed in Tokyo on Friday. Three Japanese passengers have been confirmed to have the virus.

Thomas Tsang, controller of Hong Kong's Centre for Health Protection, said two locals and one foreigner on the plane had been traced and hospitalized but had not shown symptoms.

Two Japanese passengers from the same flight who disembarked in Hong Kong were taken to hospital after being traced Saturday and had tested negative.

All five will be quarantined for seven days even if all are cleared of swine flu under Hong Kong's strict health regulations to prevent the spread of viruses.

Around 300 guests and staff at Hong Kong's Metropark Hotel were quarantined last week after Asia's first confirmed case of H1N1 turned out to be a guest at the hotel.

Hong Kong's strict anti-virus regime was introduced after the 2003 severe acute respiratory syndrome or SARS outbreak which killed 299 and infected 1,799 in the densely populated city of 7 million. (dpa)