Rakuten Inc., the operator of Japan's largest Internet shopping mall Rakuten Ichiba, admitted Friday that it had handed over credit card numbers and other personal information on its customers to nine companies that run shops on the network.

Rakuten said it has been getting complaints from shoppers upset about receiving junk mail at the e-mail addresses they used to conduct transactions with Rakuten and other incidents.

But a Rakuten official said he believes that the personal data disclosed to the nine shops was not leaked outside the online mall's network.

In 2005, Rakuten pledged in public that it wouldn't disclose the personal data of shoppers to companies that operate in the virtual mall, except for postal addresses and names needed to deliver goods ordered.