Tokyo police arrested a man Thursday suspected of illegally providing a South Korean firm with research data from Toshiba Corp. on flash memory.

Yoshitaka Sugita, 52, of Fukuoka Prefecture, was an engineer at SanDisk Corp., a semiconductor maker that had formed an alliance with Toshiba on flash memory production, the police said, adding that he had access to the data.

It is rare for a technology leak to a foreign company to lead to a criminal case.

He allegedly acquired data on NAND flash memories used in such products as smartphones around July 2008, duplicated it and handed it over to SK Hynix Inc. after he began working for the South Korean chip giant, the police said. The man later left Hynix.

The metropolitan police acted after Toshiba and SanDisk filed a criminal complaint.

In 2004, Toshiba filed a lawsuit against the Japanese unit of what was then Hynix, seeking damages for violations of flash memory patents and an injunction against the sale of the offending products.

In 2006, the Tokyo District Court ordered Hynix to discontinue sales of the products in violation and to pay ¥7.8 million in damages.