The United States has urged Japan in an annual trade report to ensure equitable competition between the Japan Post group and private firms, particularly in the insurance sector, reiterating its concerns that the market is dominated by postal life insurance.

The postal insurance system "remains a dominant force," said the 2010 National Trade Estimate, which was released Wednesday.

"The U.S. government has long-standing concerns about the postal insurance company's impact on competition in Japan's insurance market and is continuing to monitor closely the implementation of reforms," the Office of the U.S. Trade Representatives said in the report.

The report calls on Tokyo to ensure equal oversight of Japan Post's financial institutions, including Japan Post Insurance Co., and private-sector companies.