China is sending a warning to Japan's new leadership, saying the incoming prime minister must show greater respect for China's core interests, including a disputed island chain in the East China Sea.

Monday's commentary by the official Xinhua news agency comes just hours after Yoshihiko Noda was chosen as leader of the ruling Democratic Party of Japan, and a day ahead of his expected confirmation by parliament as prime minister.

Xinhua says the new Japanese government must show respect for China's territorial integrity concerning the Tokyo-administered island chain known to Japan as Senkaku and to China as Diaoyu. It says China is willing to jointly explore for resources around the islands, on condition that Japan recognize China's complete sovereignty over them.

The agency also says Noda's government should implement a “proper” policy of atonement for its crimes during World War Two, in particular by avoiding visits to a Tokyo shrine where 14 war criminals are among the honored war dead.

China and Japan have repeatedly clashed over the East China Sea islands since last year, when Japan's arrest of a Chinese fishing boat captain prompted Beijing to cut off all high-level contacts with Tokyo.

Japan formally protested to the Chinese ambassador in Tokyo last week after two Chinese patrol boats entered what Japan considers its territorial waters within 20 kilometers of the islands.

China responded that the vessels were operating legally within Chinese territorial waters.