NARITA, Chiba Pref. (Kyodo) At least 150 people have been unable to catch their connecting flights at Narita airport since Japan initiated onboard quarantine inspections two weeks ago to prevent the global spread of the H1N1 influenza virus, air carriers said.

Airlines like All Nippon Airways and Japan Airlines are providing such passengers free hotel stays since the inspections started April 28 for direct flights from Mexico and North America, which have suffered fatalities linked to the so-called swine flu.

The inspections involve three to eight quarantine officers who board each plane to check passengers for fever using thermographic cameras and ask them about their health. The measures usually take about an hour, but could take as long as four to five hours, depending on the number of passengers or if a suspected flu patient is found.

To help passengers make their flights, ANA has been delaying the departures of planes bound for Okinawa, Fukuoka, Osaka, Hiroshima as well as Singapore, Vietnam and Thailand for 15 to 30 minutes.

Nevertheless, more than 100 people have been unable to make their connections, forcing the airline to offer refunds or help the passengers switch to other airlines.

JAL said about 50 customers have missed their changeovers at Narita, forcing it to book hotel rooms, change flight plans or provide refunds.

Some passengers have complained about the delays, demanded compensation or berated the airlines for not holding their connecting flights longer.

"Not all the delays are attributable to the quarantine inspections, but they are a major factor," an ANA spokesman said. "We'd like to make as much effort as possible to provide redress to our customers."