China's assistant foreign minister on Friday urged Japan to seriously self-reflect to ensure bilateral ties get back on track, warning that continuous erroneous practices by Japan will see the relationship between it and China sink like the Titanic.

Le Yucheng made the comment at a seminar organized by the Chinese People's Institute of Foreign Affairs and the China Institute of International Studies to mark the 40th anniversary of the normalization of China-Japan relations.

Stressing the auspicious occasion, Le expressed regret that despite China's repeated solemn representations, the Japanese government had decided to "purchase" the Diaoyu Island and its affiliated islands, severely infringing upon China's territorial sovereignty and damaging the foundation for bilateral friendship.

"It caused bilateral ties to suffer a serious setback," the assistant foreign minister said, adding that Japan should abandon the idea that it can occupy the Diaoyu Islands and that sending a few envoys to China to explain the issue will be the end of it.

China hopes the Japanese government will respect history, be responsible for bilateral ties and the peace and stability of East Asia, understand the situation clearly and conduct deep self-reflection, Le urged.

Japan should have the political courage to take effective measures to defuse the Diaoyu Islands issue and stop any acts that undermine China's territorial sovereignty so that the bilateral ties can return to healthy development, Le said.

He called on Japan to build trust for the bilateral ties by respecting the understanding and consensus on the Diaoyu Islands reached between the older generation of leaders of the two countries.

"Maintaining China-Japan friendly ties is not the business of China alone. The key is that Japan should follow the path of peaceful development and prevent right-wing forces from misleading the country, and accept rather than contain China's development," Le said.

Seeking friendship and cooperation between China and Japan is in the interests of the two peoples and trends of the era. Those who block the road to cooperation will be condemned by history, he added.