Authorities have utilized bilateral tax treaties to find about ¥85 billion in undeclared income over the past decade, the National Tax Agency said Thursday.

The total includes about ¥5.7 billion subject to malicious tax evasion attempts.

Japan has concluded bilateral tax treaties with 64 countries and regions, including tax havens the Cayman Islands and Bermuda, to prevent double taxation as well as tax evasion through cooperation between tax authorities.

In addition to exchanging information through letters, agency tax officials have had direct meetings with their foreign counterparts when conducting overseas tax examinations.

"It is wrong to conclude that income hidden overseas is difficult for tax authorities to find," an agency official said.

The agency said it utilized bilateral tax treaties to make 646 requests for information from abroad in the year to March, more than twice the number the previous year. Some 70 percent of the requests were made to Asia-Pacific countries, including China and South Korea.

The number of interest and dividend income information items exchanged came to about 289,000 for the year.