Japanese police say they have arrested 14 pro-China activists who landed Wednesday on an island chain claimed by both China and Japan.

The activists arrived on the islands by boat from Hong Kong despite the heightened security of Japan's coastguard, which fired water cannons at the Chinese fishing vessel. Japanese police accuse those detained of violating immigration law, and they have sent them to Okinawa to face the charges.

The activists say the landing was aimed at countering a plan by a group of Japanese lawmakers to visit the disputed islands.

The uninhabited islands, known as Senkaku in Japanese and Diaoyo in Chinese, are a frequent flashpoint between Tokyo and Beijing. They are located in a gas-rich area and surrounded by rich fishing grounds.

The landing came as tension broke out between Japan and its neighbors on the emotionally charged anniversary of Tokyo's surrender in World War II.

In a separate demonstration, a group of South Koreans reached a set of disputed islands known as Takeshima in Japan and Dokdo in Korea. It comes less than a week after South Korean President Lee Myung-bak visited the island chain, provoking ire in Tokyo.