The government has put maritime police on alert after a group of Japanese right-wing activists announced their plan to land on Dokdo islets.

A Foreign Ministry official said the four Japanese men departed from Shimane Prefecture Wednesday aboard a small boat for Dokdo in the East Sea. The official said, however, that it is unclear whether the group will be able to attempt a landing on the islets on Wednesday.

The members of a right wing group named "Nihon Shidokai" had attempted to sail out for a landing on the South Korean islets on Tuesday but failed due to inclement weather. The rightist group had planned the landing to protest South Korea's claim to the volcanic outcroppings lying half way between the two countries.

Seoul said it will sternly deal with any attempt by the Japanese to land on the islets and threatened to seize their boat and arrest them if they violate South Korea's territorial waters.

The islets have been at the center of a long-running dispute between the two countries. Seoul holds that the islets belong to South Korea, but that Japan began to claim sovereignty over them after it colonized the Korean Peninsula in the early 20th century.