Japan says U.S. President Barack Obama has expressed regret over the alleged U.S. surveillance of senior Japanese officials.
The comments came during a phone call between Obama and Japanese Prime Minister Shinzo Abe, according to Tokyo government spokesman Yoshihide Suga.
"President Obama said he was very sorry... as the case caused a big debate in Japan," said Suga, who did not say whether Obama specifically confirmed the spying.
He added that Abe expressed his "serious concern" over the incident and noted the allegations could undermine trust between the two allies.
White House officials have not yet commented on the discussion.
Media whistleblower WikiLeaks last month published documents it says show the U.S. spied on 35 companies, government ministries, and individuals in Japan.
WikiLeaks said the intercepts related to topics such as U.S.-Japan relations, trade negotiations, and climate change strategy. It said the surveillance dates as far back as 2006, the first term of Prime Minister Abe.
It is the latest of several spying revelations that have strained relations between Washington and its allies.
In June, WikiLeaks released documents saying the United States spied on the last three French presidents, prompting a diplomatic dispute between the nations, despite friendly ties dating back to the 1700s.
In 2013, WikiLeaks reported that the U.S. National Security Agency had wiretapped German Chancellor Angela Merkel's private phone. The report sparked a political scandal in Germany and prompted an official inquiry.
The United States and Japan have been allies for more than a half-century following the end of World War II.