By Chang-Ran Kim and Miyoung Kim
TOKYO (Reuters) - Partners Toshiba Corp of Japan and SanDisk Corp of the United States separately filed civil lawsuits against South Korea's SK Hynix Inc, seeking damages over the suspected theft of data related to their flagship flash memory chip technology used in smartphones and tablet computers.
SK Hynix said on Friday it had not yet received the litigation and had no comment to make. Hynix competes with both Toshiba and SanDisk, partners in flash memory technology for nearly 15 years, in supplying chips to device makers.
The moves follow the arrest by Tokyo police on Thursday of a former SanDisk engineer suspected of improperly providing technical data to Hynix, where he later worked.
Toshiba said on Friday it had filed the suit with the Tokyo District Court. It did not disclose how much it was seeking, but said it estimates losses of at least 100 billion yen ($980 million) as a result of the alleged leak.
SanDisk said it filed its suit against Hynix and related entities in Santa Clara Superior Court, in California, seeking damages, an injunction and other remedies.
Flash memory chips, used to store data in smartphones and tablets, are a key source of profit for Toshiba, whose key competitors in the business include South Korea's Samsung Electronics Co.
In a previous case, Toshiba sued Hynix in 2004 seeking damages for the breach of its flash memory patents and an injunction against the sale of related products. The case was ultimately settled through a cross-licensing agreement with Hynix.
Shares in Hynix were down 1.6 percent on Friday morning, underperforming Seoul's benchmark KOSPI index. Toshiba was down 3.3 percent, lagging a 2.5 percent fall in Tokyo's Nikkei average.
(Reporting by Chang-Ran Kim in TOKYO and Miyoung Kim in SEOUL; Editing by Kenneth Maxwell)