Since at least 2006, the U.S. National Security Agency has been spying on a number of top Japanese government officials, banks and companies, including Mitsubishi, according to documents released by WikiLeaks on Friday. The report, named "Target Tokyo," is the latest in a number of WikiLeaks releases showing the U.S. has spied on top officials from the ally nations of Germany, France and Brazil, not just countries that are seen as potential threats.

The documents, four of which were marked as top-secret, show that the U.S. was listening in on conversations of Japanese "conglomerate, government officials, ministries and senior advisers," including the following:

"The switchboard for the Japanese Cabinet Office; the executive secretary to the Chief Cabinet Secretary Yoshihide Suga; a line described as 'Government VIP Line'; numerous officials within the Japanese Central Bank, including Governor Haruhiko Kuroda; the home phone number of at least one Central Bank official; numerous numbers within the Japanese Finance Ministry; the Japanese Minister for Economy, Trade and Industry Yoichi Miyazawa; the Natural Gas Division of Mitsubishi; and the Petroleum Division of Mitsui."

WikiLeaks said that through the spying, the U.S. had become privy to a number of Japan's internal discussions on various issues, including the contents of a confidential briefing held in Prime Minister Shinzo Abe's home. The spying on Abe's cabinet dated back to his first term in office, from September 2006 to September 2007.

"The reports demonstrate the depth of US surveillance of the Japanese government, indicating that intelligence was gathered and processed from numerous Japanese government ministries and offices," WikiLeaks said. "The documents demonstrate intimate knowledge of internal Japanese deliberations on such issues as: agricultural imports and trade disputes; negotiating positions in the Doha Round of the World Trade Organization; Japanese technical development plans, climate change policy, nuclear and energy policy and carbon emissions schemes; correspondence with international bodies such as the International Energy Agency (IEA); strategy planning and draft talking points memoranda concerning the management of diplomatic relations with the United States and the European Union; and the content of a confidential Prime Ministerial briefing that took place at Shinzo Abe's official residence."

The Associated Press was not able to independently verify the documents, but noted that WikiLeaks has a long history of publishing legitimate government leaks.

Japanese Foreign Ministry press secretary Yasuhisa Kawamura told AP that Japan and the U.S. are in communication about the NSA's "information collection" but did not provide further details, only adding that "Japan will continue to employ all the necessary measures to protect (its) information."