TOKYO • Japanese leader Shinzo Abe has told United States Vice-President Joe Biden he would have "serious concerns" if WikiLeaks claims that Washington spied on Japanese politicians were true, and has asked for an investigation.

Tokyo's Cabinet spokesman Yoshihide Suga said yesterday that Mr Biden had apologised to the Japanese Prime Minister in a telephone call for "causing troubles", without confirming the spying claims.

The whistleblower group said last Friday that it had intercepts revealing years-long spying by the US National Security Agency on Japanese officials and major companies.

"Prime Minister Abe told (Biden) that, if figures in Japan were in fact subject to these activities, it would risk jeopardising the trusting relations between allies, and he would have to express serious concern," Mr Suga told a regular press briefing.

Mr Abe "also requested that the case be investigated and that (Washington) supply an explanation".

Following the Abe-Biden call, a White House statement highlighted the countries' strong ties.

"In the call, the Vice-President underscored our strong commitment to the US-Japan alliance and thanked Prime Minister Abe for his enduring partnership," it said.

"The Vice-President reaffirmed the United States' commitment made by President Barack Obama in a 2014 presidential directive to focus our intelligence collection on national security interests."

Unlike German Chancellor Angela Merkel and French President Francois Hollande, Mr Abe did not appear to be a direct target of wiretapping - but other senior politicians, including Trade Minister Yoichi Miyazawa, were, according to WikiLeaks.

Bank of Japan governor Haruhiko Kuroda was also in the sights of US intelligence, WikiLeaks said.

The allegations came just as negotiations over the trade agreement known as the Trans-Pacific Partnership failed to reach a final deal.

The US and Japan are the two biggest economies in the 12-nation negotiations, but they have argued over key issues, including auto sector access and opening up Japan's protected agricultural markets.

Wikileaks' allegations also come at a time when Mr Abe has moved to expand the role of Japan's military, a move applauded by Washington but which is deeply unpopular at home.

WikiLeaks said the US intercepts showed "intimate knowledge of internal Japanese deliberations" on trade issues, nuclear policy, and Tokyo's diplomatic relations with Washington.

AGENCE FRANCE-PRESSE