A vehicle carrying Japanese aid workers in conflict-ravaged South Sudan came under gunfire earlier this month, but no one aboard was injured, the government's top spokesman revealed Thursday.

A group of four Japan International Cooperation Agency workers were travelling in a bulletproof vehicle in the capital Juba on the evening of July 8 when the vehicle was hit by gunfire, Chief Cabinet Secretary Yoshihide Suga told a news conference.

The workers were travelling from their office to their lodgings.

Although a cease-fire was called on July 11, tensions remain high in South Sudan after fighting erupted earlier this month between followers of President Salva Kiir and those loyal to Vice President Riek Machar, killing scores of people.

Members of Japan's Ground Self-Defense Force serving in a United Nations peacekeeping operation have remained in Juba. Under Japanese law, they can only participate in such operations in areas where conflicting parties have ceased fighting.

"Armed conflict as defined under the PKO cooperation law has not broken out in the area of activity, and we do not feel that the five principles (required for SDF participation) have been broken," Suga said.

Earlier this month, Japan airlifted its nationals out of the capital via the SDF's base in Djibouti.