A senior Tokyo police official tasked with keeping the city's roads clear of drunk drivers has been arrested for driving under the influence, police said.

The deputy inspector, on his way home from a camping site, was caught late on Monday after bumping into another car and veering off the road, said a police official in Ibaraki.

"He smelled of alcohol and he couldn't walk straight," the official said.

Local media said the arrested official had been in charge of a campaign to stop drunk driving, handing out stickers to bars and restaurants around the city.

"It is inexcusable for a member of the police to have caused this case and we plan to deal with it strictly," Tsutomu Sato, the head of the National Public Safety Commission told reporters.