Japan on Friday warned China that its reputation was on the line as companies rushed to recall Chinese-made food after hundreds of Japanese said they fell ill from dumplings.
At least six major foodmakers ordered recalls of frozen and prepared foods that were suspected to have been produced at the same Chinese factory in Heibei province behind the food safety crisis, company officials said.
Big household names including Ajinomoto, Glico, Katokichi and Kibun recalled more than 30 dishes effective Friday including Chinese-style stir-fries, skewered and barbecued pork, beef tongue and curries.
China -- Japan's largest trading partner and second biggest supplier of imported food -- has said it found no pesticide in the dumplings as alleged in Japan but pledged an investigation.
Japanese officials warned that China needed to be thorough.
China "must exert all its efforts to make sure this will not trigger sentiment in Japan against products made in China," Trade Minister Akira Amari said.
Foreign Minister Masahiko Komura said separately: "We can limit the negative impact on Japan-China relations to a minimum if both countries cooperate to investigate the cause and to deal correctly with any reoccurence."
As supermarkets pulled the suspect food from shelves, the scare even spread to Japan's military which, despite sometimes fraught political relations with Beijing, bought frozen pork cutlets from the same Chinese factory.
Although no illnesses were reported, Defence Minister Shigeru Ishiba ordered officials to comb through army kitchens and throw out any suspicious food.
China's soaring economic growth is tied to the strength of its giant manufacturing sector, which has become the world's factory.
But the country's image has been hit by increasingly frequent reports of dangerous food or other products being sold overseas, ranging from tyres to toothpaste.
The scare in Japan started when Japan Tobacco Foods, part of the nation's giant cigarette maker, announced on Wednesday that insecticide was found in its imported Chinese meat dumplings.
The health ministry set up a call centre Friday to respond to a flood of inquiries from consumers. A total of 175 people called to say they had stomach aches, nausea or other symptoms from the dumplings, a ministry official said.
Media reports have given different figures. Kyodo News said 498 people told authorities, including at the local level, that they felt ill after eating the dumplings.
Ten people were confirmed to still be ill, although their conditions were improving, the health ministry official said.
A five-year-old girl in suburban Tokyo who had been in serious condition improved slightly on Friday, with doctors able to remove a ventilator, police said.
Japanese importers also came under fire for quietly investigating rather than notifying the public when the first reports of sick consumers emerged in late December.
"It's a problem that it took time to communicate and deal with the issue," Prime Minister Yasuo Fukuda told reporters.
"The Fukuda cabinet is consumer-conscious, so this is a very big issue. It should be firmly dealt with," he said.
Food safety inspectors from the Japanese importers including Japan Tobacco arrived in China's Heibei province on Friday to inspect the suspicious factory, television footage showed.
Police also said they were investigating a report that there was a three-millimetre tear in a pack of 20 dumplings that made a family of three fall ill.