Japanese and South Korean negotiators raced Thursday to avert a clash over disputed islets as Seoul accused Tokyo of neocolonial ambitions and warned of a possible high seas confrontation.

Behind-the-scenes talks on a diplomatic solution came even as tensions mounted over a Japanese plan to survey the seabed near the islets, known as Takeshima by Japan and Dokdo by South Korea, which has effectively controlled them since 1954.

The crisis prompted South Korean Foreign Minister Ban Ki Moon to summon Japanese Ambassador Shotaro Oshima early Thursday to demand a halt to the project. Oshima rejected the same request on April 14 when he was summoned to the Foreign Affairs and Trade Ministry by South Korean Vice Foreign Minister Yu Myung Hwan.