A spat between Japan and China over the 2004 suicide of a diplomat at the Japanese Consulate General in Shanghai continued Thursday as Chief Cabinet Secretary Shinzo Abe urged Beijing to give a "sincere response" over what has been reported as an attempt to extort intelligence.

"We want to see a sincere response from the Chinese side," Abe told reporters.

Beijing responded in kind, saying later the same day that Tokyo's claim that Chinese agents were linked to the death "lacks reason." The diplomat, who according to some reports was in charge of encrypted classified communications, was allegedly being blackmailed for intelligence by Chinese agents exploiting his affair with a hostess.