TOKYO — Emperor Akihito, whose father announced his exhausted country’s surrender in World War II, expressed “deep remorse” for the conflict on Saturday at a memorial service on the 70th anniversary of the war’s end.

The words were not new for the emperor: He has often spoken of remorse over the war, and he has done so increasingly in recent years, in meetings with foreign leaders and visits to sites where battles once raged.

But they were an unfamiliar addition to the short and highly ritualized statement he delivers each year at the memorial ceremony on Aug. 15. In a year of controversies in Japan over memories of the war and the role of the country’s modern military, they could reinforce a belief among some observers that Emperor Akihito is taking a quiet stand against the policies of Prime Minister Shinzo Abe.

The emperor’s statement came a day after Mr. Abe, a conservative nationalist, made his own keenly awaited remarks about the war, in which he endorsed past expressions of contrition by Japanese leaders — including the same “deep remorse” — but chose not to make a new apology of his own, a departure from past practice.