Japan Airlines International Co. is suing the All Nippon Airways group for 10 billion yen, accusing it of violating a JAL patent on online corporate ticket bookings, company officials said Tuesday.

JAL filed the suit at the Tokyo District Court, saying it obtained a business model patent in April 2001 for the system, which allows client companies to book tickets for their employees and settle payments over the Internet.

The employees use credit cards for identity verification when checking in for flights.

About 11,000 companies use the JAL system, which was launched in January 1999.

ANA started providing the same service in January 2000 and serves about 10,000 companies.

According to ANA officials, they received a warning from JAL in March 2000 regarding the alleged patent violation. The two carriers negotiated on the matter until June 2001.

"To our knowledge, the conclusion was that it did not constitute a violation," an ANA public relations official said.

Yet ANA said it received another warning notice in April.

"We firmly believe there was no violation of the patent," ANA said in a statement. "We cannot figure out why they brought the case to court at this time."

JAL also issued a statement, saying, "There was inadequate explanation (from ANA) and we had no choice but to file the lawsuit in order to protect our shareholders."