Yahoo Japan Corp. started posting on its Web site Wednesday the family names and bank account numbers of people who have repeatedly engaged in fraudulent and other illicit transactions on its auction sites.

The firm, Japan's top Internet portal, identified about 100 accounts of people who, using Yahoo IDs, have allegedly engaged in illegal practices, including failing to send products that have been paid for by successful bidders.

It became the first Internet portal in the country to identify the bank accounts of people allegedly engaged in illegal practices on auction sites in a bid to increase the security of online transactions.