NAGANO -- Just as some venues for the Olympics were taking shape last June, six of Ramilo DeLeon's friends suddenly ended up in police custody after a crackdown on illegal immigrants.

Since that day, DeLeon, a Filipino construction worker, has spent several sleepless nights worrying about another sweep. Fearing police, he closeted himself in his apartment, leaving home only for work. "(The foreign workers) have worked very hard for years to prepare Nagano for the Games. But once our work was done, we were thrown away like toys," said DeLeon, 29, who lost his job in December and has yet to receive his pay for the month.

Last year, Nagano Prefectural Police arrested or deported 397 foreigners, conducting 13 raids at homes of illegal foreign workers and related locations as of November. The arrest figure nearly doubled from the previous year, citizen groups claim, criticizing police for violating the rights of foreign workers by stepping up the crackdown after exploiting their labor for years.

Police launched the Operation White Snow sweep in January last year to crack down on gangsters, prostitutes and other undesirable elements before visitors arrive for the Winter Games. Human rights activists suspect the operation also targeted foreign workers, who arrived in the prefecture in search of jobs after Nagano was selected in 1991 to host the Games.

The number of foreign workers doubled from 3,019 in 1993 to 5,904 last year, according to a prefectural survey.

"Police have been extremely opportunistic. They have ignored foreign workers' contributions to Japan and suddenly tightened control over them," said Monica Nakamura of Shinshu Network for Foreigners' Human Rights.

Police argue that such criticism is unfounded, and that the operation was never aimed at foreigners. They point out that there were 506 foreigners arrested in 1994 for staying in Japan illegally, 410 in 1995 and 209 in 1996, indicating the crackdown was consistent, but decreased in 1996. But Nakamura recalls seeing many foreigners near construction sites in the Shinonoi district, where the Olympic Village and stadium for the opening and closing ceremonies are located.

Police seemed to condone their existence when the immigrants were busy building the sites, she said. "And it is not the number of arrests that is in question. We should look at the fact that many foreigners here went through a tremendous degree of agony, fearing a police crackdown," Nakamura said, noting many foreigners came to her in a state of panic for help during the past six months.

Police nevertheless insist the operation merely intensified the crackdown on red light businesses, which happened to include many foreigners. "Between 70 percent to 80 percent of the arrested foreigners were women," said Toshio Gomyo of the Nagano police.

But such women also contributed to the Olympics indirectly by entertaining the officials and staff involved in the event, Nakamura argued. "International participation has been called for at the Nagano Games. But this sounds so vain, considering how much foreigners are exploited in the process," she said.