Emperor of Japan Akihito on Saturday expressed his "deep remorse" over past war for the first time at an annual national memorial service.

Akihito had expressed remorse previously but not at the annual service at the Nippon Budokan Hall in Tokyo.

In a closely-watched statement released on the eve of the 70th anniversary of Japan's surrender in WWII, Prime Minister Shinzo Abe reiterated previous governments' apologies over Japan's past wartime actions, but refrained from offering a fresh apology himself.

He also claimed that Japan's future generations must not "be predestined to apologize" for the country's role in the conflict.