A female Japanese police officer resigned Friday after it was revealed that she drove police vehicles without a license between 10 and 20 times since around November.

"I thought I'd be forced to resign from the criminal investigations bureau if I admitted I didn't have a license," the Saitama prefectural police quoted the 22-year-old as saying.

The police said earlier Friday they had referred the case of the officer, who belonged to the Kawagoe Police Station's division of criminal affairs, to prosecutors and suspended her for six months.

Her referral to prosecutors was based on the allegation that she drove police cars four times in the city of Kawagoe between Jan. 10 to Jan. 15.

Her secret came to light when she was questioned following an accident in the Kawagoe police parking lot on Jan. 16. She was then forced to reveal that she only had a license for two-wheeled vehicles.

In reports submitted every April and October, the police officer wrote that she possessed a license to drive cars as well one for medium-sized vehicles.

"It is extremely regrettable that a police officer has committed such an act," said Katsuhiko Kondo, the prefectural police department's chief inspector. "We will do our best to ensure this type of incident will not be repeated by doing our utmost when advising our officers."