A deal to combine the frozen food businesses of Japan Tobacco and Nissin Food Products has been done in by tainted dumplings.

Ten people in Japan fell ill after eating the pesticide-laced dumplings, called gyoza, which were imported from China by a unit of Japan Tobacco. Nissin, known as a pioneer of instant noodles, then scrapped the merger, citing “differences on the issue of safety.”

Japan Tobacco, the world’s third-biggest cigarette maker, had planned to combine its frozen business with that of Nissin after buying a third frozen food firm, Katokichi, for $1 billion and selling a 49 percent stake in Katokichi to Nissin.

A Chinese food safety official said that the dumplings may have been deliberately contaminated by “a small group who do not wish development of Sino-Japanese friendship.” The Japanese health minister has also raised the possibility of intentional dumpling poisoning, and Japanese police are investigating the case on suspicion of attempted murder.

Japanese media have also reported Japan Tobacco faces an insider trading probe after its shares tumbled 8 percent on January 28, two days before it announced it was recalling the dumplings.