Japanese Prime Minister Shinzo Abe has reiterated Tokyo's hard-line position on the Diaoyu Islands, during a tour of Okinawa, amid continuing tension over the East China Sea islands.

Observers said a speech by Abe on Saturday represented a setback.

Abe was commenting on patrols by Chinese government vessels in the waters off the islands, while praising officers of Japan's regional coast guard office on the southern island of Okinawa.