Wikileaks Obama Japan Shinzo NSA
Barack Obama with Japanese Prime Minister Shinzo Abe at the White House in April 2015Reuters

US President Barack Obama has apologised to Japan over revelations from WikiLeaks that the US National Security Agency (NSA) undertook systematic mass surveillance of Japanese government officials and major companies. In a telephone conversation with Prime Minister Shinzo Abe, Obama expressed regret for causing concern but failed to confirm whether or not the spying claims were true.

"President Obama said he was very sorry... as the case caused a big debate in Japan," said Yoshihide Suga, a spokesperson for Abe. "Prime Minister Abe told [Obama] that, if the Japanese people concerned were subject to these activities, it would risk jeopardising trusting relations between allies."

The alleged spying dates back to Abe's first term in office, lasting from September 2006 until September 2007. Beyond Abe, other high-profile targets reportedly included car-manufacturing giant Mitsubishi.

Following the revelations from WikiLeaks, the whistleblowing organisation's investigations editor Sarah Harrison speculated that climate change policy enacted by Japan, as well as the country's industry, may well have been different had the NSA not spied on negotiations.

"Today's publications shows us that the US government targeted sensitive Japanese industry and climate change policy," Harrison said. "Would the effectiveness of Japan's industry and climate change proposals be different today if its communications had been protected?"

Earlier this month, Abe called for a probe into the spying claims and stated that if they proved to be true then it risked "jeopardising the trusting relations between allies". An explanation from Washington was also requested, though it has yet to be made publicly.

The US has previously been implicated in spying allegations in Brazil, France and Germany, following revelations from NSA whistleblower Edward Snowden in 2013. An investigation into claims that German Chancellor Angela Merkel's phone was tapped was dropped in June due to a lack of evidence.