Staff writer OSAKA -- Police here recently announced that after a yearlong investigation, they have broken up an underground banking operation that funneled an estimated 20 billion yen a year to China through an elaborate network of falsified accounts in Tokyo and Osaka. Since early 1999, 10 Chinese nationals have been arrested and charged with illegal entry, forging documents and various violations of the Foreign Exchange and Foreign Trade Control Law. The latest arrests came last month, when two Chinese whom police believed played key roles in sending the money abroad were arrested at an Osaka apartment. The arrests and breakup of the ring come nearly two years after police formed a special task force to deal with Chinese criminal activity in Japan. The extent of the underground banking network -- more than 50 falsified accounts at six legitimate banks in Tokyo, three in China and one in Osaka -- makes it the largest violation of the foreign exchange law to date, police said. Much of the money was collected from Chinese working illegally throughout Japan, but primarily in Osaka. Although police believe much of the cash came from the sale of stolen goods, falsified pachinko cards and pachinko earnings, some may have also been from Chinese who paid Japanese or Chinese human smugglers, as well as Chinese working in the sex industry. The underground banking system had been in place since at least 1998. The first break in the investigation came with the arrest in October 1998 of alleged ringleader Chan Ton Son, a 30-year-old Chinese man living in Tokyo, and the arrest last February of fellow conspirator Li Fan, a 44-year-old Chinese man living in Osaka. Both were charged with a number of crimes, ranging from violation of the foreign exchange law to illegal entry. Another eight Chinese, unnamed by police, were arrested at the same time for immigration violations and are believed to be accomplices of Chan An Li. During questioning, police learned that Li, based in Osaka, collected money from 83 illegally employed Chinese workers, taking a 1 percent commission. The money was then deposited in a legitimate Osaka bank. Next, it was wired to Tokyo, where it was withdrawn by Chan and, along with money that came in through other prefectures, deposited in another dummy account. From there, the money was sent to Hong Kong. As the investigation progressed, further evidence of an extensive network was uncovered. Between October and December 1998, about 1.1 billion yen was sent to China this way. Chan is believed to have set up more than 40 different accounts at six Tokyo banks and 12 accounts in four banks in Hong Kong and Shanghai to funnel the money. In October 1998 alone, about 1.8 billion yen was sent to China this way. Based on this evidence, police estimated that the underground bank system was sending 20 billion yen a year to China. They also constructed a flow chart from information given by Chan, Li and others who were arrested that showed how money traveled from Osaka to Tokyo to China. The investigation continued with no further arrests until last November, when Wang Mei, 21, and He Jia Jie, 20, both living in Osaka, were arrested for sending money abroad illegally. Wang was caught after she allegedly attempted to forge bank documents to send money from Osaka to Hong Kong. During questioning, it was learned that Wang had been placed in charge of collecting money from Chinese in Osaka and Tokyo and wiring it to a bank in Hong Kong. Between April and May 1998, Wang allegedly sent four payments to Hong Kong totaling 35 million yen. Between last August and October, the payments totaled 1.2 billion yen. Wang, originally from Fuchien Province in southern China, arrived in Osaka in August 1998, only two months before Li was arrested. While no direct link between Li and Wang has yet been established, police suspect she may have taken over Li's operations after his arrest. He, who was living with Wang, was charged as Wang's accomplice. Police would not say whether any of the Chinese arrested thus far were members of Snakehead gangs, many of which operate in Fuchien, but said they are investigating the possibility. They added that the investigations into Chinese money laundering are continuing.