South Korea has expressed deep regret that Japan's leader did not repeat his predecessors' apologies for the country's aggression during World War II.

Prime Minister Shinzo Abe told Asian and African leaders in Indonesia on Wednesday that Japan has "feelings of deep remorse" over the war. But he did not express a "heartfelt apology" for Japan's past "colonial rule and aggression" — phrases that previous prime ministers have used in official statements about the war.

Abe's decision is fueling speculation that he will also not apologize in a key statement in August marking the 70th anniversary of the end of the war.

South Korea's Foreign Ministry on Wednesday expressed "deep regret because Prime Minister Abe omitted the key expressions of apology and repentance."