SAN FRANCISCO, Dec 22 (Reuters) - Uber said on Thursday its self-driving test cars had left California to begin testing in Arizona, after California revoked the registration of the cars, which it said lacked the proper permits.

"Our cars departed for Arizona this morning by truck," said an Uber spokesperson. "We'll be expanding our self-driving pilot there in the next few weeks."

San Francisco was to be Uber's second testing ground for its self-driving cars after Pittsburgh, but immediately after its Dec. 14 launch it became embroiled in a dispute with the California Department of Motor Vehicles, which requires a permit to test autonomous vehicles on public roads.

(Reporting by Alexandria Sage)