With a mournful bow, Emperor Akihito has paid his respects at a hilltop war memorial near Manila to the largest number of Japanese invasion troops who died outside their homeland in World War II.

Clad in black and accompanied by Empress Michiko, he and Michiko each laid a bouquet of white flowers and silently prayed at a marble cenotaph in the Japanese memorial garden along Lake Caliraya in Laguna province southeast of the Philippine capital.

Some of the 170 relatives of Japanese soldiers wept quietly.

Akihito did not speak at the ceremony but in his only public remarks related to Japan's wartime aggression he said at a state banquet on Wednesday that Japan should never forget the massive loss of lives in the war 71 years ago.