Two police officers in Chiba Prefecture were arrested separately Wednesday on suspicion of driving without a license, police said.

Kiyoto Ishimoto, a 51-year-old police sergeant at Chiba Minami Police Station, and Norito Toyoda, a 31-year-old senior police officer at Yachiyo Police Station, were held on suspicion of violating the Road Traffic Law, the police said.

Ishimoto, who does not possess a motorcycle driver's license, had allegedly ridden a police motorcycle on three occasions since November. Toyoda, who only has a motorcycle driver's license, had allegedly driven police cars on three occasions since June 2000, the police said.

Police said Toyoda managed to pass three in-house checks by tampering with his motorcycle driver's license to make it look like one for a car and then submitting photocopies of the doctored document.

"We regret that we weren't able to discover these cases earlier," said Tsukasa Tago, personnel division chief of the Chiba prefectural police. "We offer our deepest apologies and promise to prevent such matters from happening again."