Senior Vice Foreign Minister Ichiro Aisawa will announce the decision at an international donor conference in Oslo starting Monday to address the reconstruction of Sudan, the sources told Kyodo News.
Japan suspended government aid to the country because of the conflict.
The Sudanese government and the rebel Sudan People's Liberation Army agreed to a truce in January following the conflict which lasted more than 20 years.
The sources said Japan will announce the aid in consideration of the fact that the issue is expected to be the main theme for the summit meeting in July in Gleneagles, Scotland, and to highlight Japan's contribution in its efforts aimed at gathering enlisting support from the world for its bid to win a permanent seat on the U.N. Security Council.
Japan also plans to seek participation in some way in the planned U.N. peacekeeping operations in Sudan. Government sources earlier said that Japan will consider dispatching Foreign Ministry officials and civilian experts to help with the mission.
The Japanese aid is expected to be used in land-mine removal projects, promotion of disarmament and social rehabilitation of former soldiers. Promotion of refugee repatriation and supporting the new Sudanese government are also included.
The grant for Sudan is one of the major pillars of Japan's assistance measures for Africa which will be announced by Prime Minister Junichiro Koizumi at the Asia-Africa summit to be held in Indonesia from April 22.