Former site of Unit 731 of the Japanese Imperial Army in Harbin, northeast China's Heilongjiang Province. (File photo: VCG)

BEIJING, April 29 (Xinhua) -- China again demands that Japan accelerate the process of addressing abandoned chemical weapons (ACWs) as it is Japan's unshakable responsibility, give back to the Chinese people their clean homeland and remove the biggest obstacle to realizing a world free of chemical weapons, Chinese foreign ministry spokesperson Lin Jian said on Wednesday.

Lin made the remarks at a regular news briefing when answering a query related to the 29th anniversary of the entry into force of the Chemical Weapons Convention, which falls on Wednesday.