Incidents of remittance fraud committed through postal services, including registered mail, rose by 2 1/2 times last year to 482, up from 189 incidents in 2004, according to the National Police Agency.

The NPA said it was able to confirm the means of transfer in 17,306 cases of remittance fraud last year. Postal services are becoming an increasingly popular way of sending money, and the agency warned that scams involving cash transfers using methods other than regular bank accounts are likely to continue rising.

Experts suspect the surge in swindles conducted through the post may be due to stricter rules on customer identification and record-keeping at financial institutions, and measures to prevent fraud in deposit accounts. The legal changes, which took effect in December 2004 and include a ban on the sale of bank accounts, may have made traditional types of fraud more difficult.

The NPA has discovered about 160 post office boxes around the country used by fraudsters to collect money. It reported the information to Japan Post last month to prevent further illegal acts. With this information, Japan Post has prevented two cases of postal fraud so far, police said.

Last month, postal workers in the city of Osaka halted a fraudulent transaction in which a Hiroshima man nearly sent 800,000 yen to Osaka as a deposit for a nonexistent loan. Post office staff noticed that the post office box specified for the transaction was on the NPA list and urged the sender to contact police.

A man in Aomori Prefecture sent 100,000 yen to a post office box by registered mail, but a postal worker in Tokyo recognized the suspicious address and prevented the swindle.

Net wire transfers are also a favorite method of fraudsters, and Japan Post has tightened rules to prevent payments to suspicious addresses.