Such usage has resulted in losses running into millions of dollars for credit card companies, reported Kyodo news service which investigated the problem. The fraud goes on because the in-flight staff is unable to perform online authorization of credit card use, police said.

Police in Chiba prefecture, which has jurisdiction over Narita International Airport, Japan's largest international gateway, has opened an investigation into the fraud, saying they suspect several cross-border rings are involved.

Chiba police say they have identified one such ring, made up of a dozen members including Thai and Filipino nationals. Authorities are considering involving the Interpol in the investigation.

The Kyodo investigation showed Japan Airlines had reported about 10 cases of fraud with losses running up to about $1,900 per case.

"One method for online (authorizations) without affecting (cockpit) instruments is to transmit radio waves to a satellite but (that) would require hundreds of millions of yen in investment per aircraft,'' a JAL official told the news service.

Other airlines' anti-fraud measures include capping the maximum purchase per customer and checking credit cards against passports, the report said.