Japan's foreign ministry has instructed its officials to refrain from taking Korean Air flights for one month starting on Monday in protest of the airline's flight by its first Airbus A380. Japanese embassy officials in Seoul also visited Korean Air this week to protest the flight.
"The Japanese measure, regarded as a sort of sanction against a private company, can hardly be understood," South Korean Foreign Ministry spokesman Cho Byung-jae told reporters.
"In this context, we delivered our strong regret and disappointment and called for Japan to immediately withdraw the measure," Cho said.
Cho said the South Korean government will take "stern" measures regarding the issue, but didn't specify what measures it would take.
"We will watch what measures Japan will take," the spokesman said.
Officials at Korean Air said they had no comment on the issue, calling it a matter between the governments of South Korea and Japan.
Korean Air Chairman Cho Yang-ho watches Dokdo during a test flight of A380 jet on June 16. (Yonhap file photo)
Japan's claims to the Dokdo islets in the East Sea have long been a thorn in relations between Seoul and Tokyo.
South Korea rejects the claims as nonsense because the country regained independence from Japan's 35-year colonial rule in 1945 and reclaimed sovereignty over its territory, including Dokdo and many other islands around the Korean Peninsula.
Tensions between South Korea and Japan resurfaced in April after Japan's Cabinet approved the "Diplomatic Blue Paper" report for 2011 with claims to the islets, and its education ministry approved a series of school textbooks claiming the islets as Japanese territory.
Another foreign ministry official, who spoke on the condition of anonymity, said, "We can't accept any protests from the Japanese side over our national airline's flight to our territory."
On Sunday, Japan's chief envoy to the stalled multilateral talks on North Korea's nuclear program, Shinsuke Sugiyama, will visit South Korea, the ministry official said.
The South Korean ministry also plans to lodge a protest with Sugiyama over Japan's temporary ban on bookings with Korean Air during his visit, according to the official.
The six-party talks, involving the two Koreas, the U.S., China, Japan and Russia, have been stalled since late 2008.