Japanese investigators have obtained internal meeting minutes detailing how five oil distribution companies coordinated diesel fuel price increases, according to sources familiar with the case. The Tokyo District Public Prosecutors Office's special investigation unit has indicted the five firms on charges of violating Japan's Antimonopoly Act for allegedly forming a cartel to fix the selling price of diesel fuel supplied to transport operators in the Tokyo area. The discovery of written records documenting the price-adjustment process strengthens the evidentiary basis of what is one of the more significant fuel market collusion cases to come before Japanese courts in recent years.