TOKYO (AP) — An unauthorized landing by Japanese activists on an island at the center of a dispute with China is sparking nationalist outrage and fueling calls on both sides for aggressive government action that some fear could lead to an escalation of tensions.

Japanese authorities on Monday questioned the 10 Japanese, including five local assembly members, who swam ashore on the disputed island the day before.

Criminal charges were not expected.

Japan's chief Cabinet spokesman Osamu Fujimura called the landing "regrettable" because it was done without government approval.

Beijing has protested and the landing has generated demonstrations in several Chinese cities. The island is part of a disputed chain called Senkaku in Japanese and Diaoyu in Chinese.