A food scare from the frozen dumplings, which made 10 Japanese people sick, stirred intense media coverage earlier this year just as Beijing and Tokyo were trying to cement an improvement in their often-frayed ties.
The dumplings will likely be on the agenda when Prime Minister Yasuo Fukuda meets with Chinese leaders Hu Jintao and Wen Jiabao on Friday in Beijing, where he will attend the Olympic Games opening ceremony, the government has said.
Foreign Minister Masahiko Komura said China had told Japan in early July that the Chinese-made dumplings had also caused food poisoning in China, but that the information should not be disclosed since the case was still under investigation.
"When the provider of the information asks that it is not disclosed, we don't," Komura told reporters in a group interview.
"This is the rule when handling information," he said.
A senior lawmaker from the main opposition Democratic Party criticised the lack of disclosure. Media also questioned the move given public concerns over the safety of Chinese-made food.
"This was an intentional cover-up," Kenji Yamaoka, parliamentary affairs chief of the Democratic Party, was quoted as saying in local media.
The dumplings have long been a headache for the unpopular Fukuda, who came under fire for taking too long to alert the public after the first consumers fell ill in late December.