Police decided Monday to send papers to public prosecutors this week on three officials of a firm whose tanker truck exploded on a Tokyo expressway in October, injuring 25 people, investigative sources said.

The Metropolitan Police Department plans to send papers on Shunichi Yokota, 61, the president of chemical processing firm Nihon Densan Kogyo Ltd., located in Tokyo's Chiyoda Ward, and two other company officials on suspicion of negligence resulting in injury and destruction by an explosive.

The truck was carrying about 500 liters of hydrogen peroxide when the explosion occurred, but had previously carried copper chloride solution. Police believe some copper chloride remained in the tank due to insufficient cleaning and reacted with the hydrogen peroxide, causing the blast.

Hydrogen peroxide, which is used in bleaches and germicides and can cause serious skin inflammation, is volatile and can blow up when it reacts to other chemicals. It is usually transported in single-purpose tanks.

The truck exploded Oct. 29 in Minato Ward on Route 2 of Tokyo's Metropolitan Expressway, injuring 25 people.