Anti-riot policemen use their shields to push back protesters making their way to the US embassy during a protest against the upcoming visit of US President Barack Obama next week, in Manila on Wednesday. Romeo Ranoco / Reuters

Beijing is adamantly opposed to the Diaoyu Islands being placed under the US-Japan defense treaty, a Foreign Ministry spokesman said on Wednesday.

His comments came after US President Barack Obama, in a rare public statement ahead of his visit to Tokyo, committed US forces to back Japan in the event of a conflict over China's Diaoyu Islands.

In a written interview published on Wednesday by Japan's leading newspaper Yomiuri Shimbun, Obama said the islands "fall within the scope of Article 5 of the US-Japan Treaty of Mutual Cooperation and Security".