A three-day conference on African development kicked off Wednesday in Yokohama, as Prime Minister Shinzo Abe pledged to aggressively promote private-sector investment in Africa in his opening speech but failed to set a new numerical target on funds to be funneled to the continent.

Facing dozens of top African leaders at the Tokyo International Conference on African Development, Abe claimed the Japanese private sector invested $20 billion in Africa over the past three years.

"I make this pledge to you. The government of Japan will put forth every possible effort so that the power of Japanese private investment of $20 billion in three years should, in the years to come, be surpassed anew from one day to the next," Abe said, although he did not mention any specific investment goal.