China urged Tokyo to swiftly address the matter and follow up on related issues, the Japanese Embassy in Beijing told the Kyodo news service.
Chinese Foreign Minister Li Zhaoxing summoned Japanese Ambassador Koreshige Anami to the Foreign Ministry over the Aug. 4 leakage of mustard gas in Qiqihar, Heilongjiang Province, that killed one man and injured dozens of people.
Noting that Japanese Prime Minister Junichiro Koizumi vowed to "sincerely" deal with the incident when he met with China's vice-premier Wu Bangguo in Tokyo last month, Zhaoxing said the Chinese people and victims of the incident are very dissatisfied with Japan's response thus far.
The poisonous gas leak occurred as containers of mustard gas, left behind by retreating Japanese forces, were uncovered at a construction site in Qiqihar.
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