Dokdo/Takeshima are a group of small islets located in the waters between
Tokyo protests at South Korean MPs' visit to disputed islands
Tokyo protests at trip in which Seoul lawmakers aimed to assert their nation's control of islands
Agence France-Presse in Seoul
A group of South Korean lawmakers yesterday visited an isolated set of islands at the centre of a territorial dispute with Japan - prompting an immediate protest from Tokyo.
Seventeen members of the parliamentary National Defence Committee flew to the Dokdo islands (known as Takeshima in Japan) on military helicopters for a day-long visit, an aide to committee member Han Ki-ho said.
The trip - described as a government inspection session - was aimed at checking security measures around the islands, which were guarded by the South Korean coastguard, the aide said.
The lawmakers shouted slogans with a placard reading "Dokdo is our land. We will defend it".
Japanese Chief Cabinet Secretary Osamu Fujimura, who on Monday urged the Seoul MPs to cancel their trip, said it was "extremely regrettable" that his call had gone unheeded.
"We strongly protest at it and we are urging South Korea to prevent future incidents," Fujimura said in Tokyo.
The islands, which lie between the two countries, are controlled by South Korea but claimed by both nations.
The long-standing row over ownership boiled over in August when South Korean President Lee Myung-bak made a surprise visit to the islets.
Tokyo said the trip, the first ever by a South Korean president, was deliberately provocative.
Lee said it was designed to press Japan to settle lingering colonial-era grievances, including the issue of Korean women forced into sexual slavery for Japanese troops during the second world war. Japan colonised Korea from 1910 to 1945.
Japan is embroiled in a separate row with China over the disputed Diaoyu islands, which it calls the Senkakus.