Tokyo  - Japan's Narita Airport began checking temperatures of passengers arriving mainly from Mexico Saturday after a swine influenza outbreak killed at least 20 people, media reports said.

The quarantine office's thermographic imaging device detected no signs of infection on 177 passengers and crew members who arrived at Narita Saturday morning from Mexico, Jiji Press quoted airport authorities as saying.

The office was to offer telephone counseling services later in the day, and the government has set up a liaison office to gather information on the outbreak at the crisis management centre of the prime minister's office.

Meanwhile, the Agriculture, Forestry and Fisheries Ministry instructed animal quarantine offices nationwide to examine any live pigs brought into Japan for signs of virus infection.

There has been no outbreak of swine flu in Japan, the ministry said.

Mexican authorities confirmed Friday the deaths of 20 people due to swine influenza over the past three weeks, while a further 48 deaths were suspected from the disease.

The situation is so dire that Mexico City closed its schools and President Felipe Calderon cancelled a visit to the northern city of Ciudad Juarez. (dpa)