Japan has told its diplomats to avoid Korean Air flights for one month in protest at the carrier\'s recent overflight of islands disputed between the two nations, an official in Tokyo said Thursday. Seoul has fired back in the latest flare-up in their long-running spat over the rocky Sea of Japan (East Sea) islets, known as Dokdo in South Korea and Takeshima in Japan, and demanded Japan reverse the ban. The protest by Japan came after Korean Air operated a demonstration flight with an Airbus 380 on June 16 over the islands, carrying South Korean business executives and journalists, the Japanese official said. Japan\'s Foreign Minister Takeaki Matsumoto \"instructed us not to take Korean Air flights for one month from next Monday\", said a Japanese foreign ministry official who spoke on condition of anonymity. \"It is the first time that such a measure has been taken.\" Japanese embassy officials in Seoul also visited Korean Air this week to protest the flight, Yonhap news agency reported. A South Korean foreign ministry official, also speaking on condition of anonymity, told AFP: \"We don\'t accept any protests from Japan over our national airline\'s flight to our territory. \"We demand Japan apologise for lodging a protest with a private company and immediately withdraw its measure against Korean Air.\" South Korea, which was colonised for over three decades by Japan until 1945, has sought to strengthen its control over the islets after Japan in March authorised new school textbooks reasserting its claims to them.