A self-driving Uber car is seen crossing San Francisco's Golden Gate bridge. Picture: Uber

San Francisco, California - Uber has taken its self-driving cars off San Francisco streets, halting the autonomous programme just a week after its launch as the company faced a regulatory crackdown.

The California Department of Motor Vehicles said on Wednesday it had revoked the registration of 16 Uber self-driving cars because they had not been properly permitted. For the past week, the agency was demanding that Uber shut down its programme and comply with regulations requiring a permit to test self-driving cars on public roads.

Uber said it didn't need a permit because its cars required continuous monitoring by a person in the car.

San Francisco was supposed to be Uber's second testing ground for its self-driving cars, after they were unveiled in Pittsburgh, Pennsylvania in September.

"We're now looking at where we can redeploy these cars," an Uber spokeswoman said, "but remain 100 percent committed to California and will be redoubling our efforts to develop workable statewide rules.

California defines autonomous vehicles as having the capability to drive "without the active physical control or monitoring of a natural person."

Public safety measure

Uber has argued that the law does not apply to its cars, which cannot stay in autonomous mode continuously. A driver and an engineer are in the front seats to take over frequently in sticky traffic situations such as construction zones or pedestrian crossings.

Uber's defiance was met with threats of legal action from the Department of Motor Vehicles and the state attorney general.

The DMV told Uber that if it had obtained a permit, the regulator would have given the green light to the self-driving pilot. Director Jean Shiomoto said in a letter sent to Uber on Wednesday that she would "personally help to ensure an expedited review and approval process," which she said could take less than three days.

The permit process is largely seen as a public safety measure, as regulations also require that companies provide the DMV with accident reports. Uber, however, has complained that its home state has favoured complex rules over technological innovation.

It is not yet clear whether Uber will apply for the permit or simply take the self-driving cars to another state.

Another 20 companies exploring self-driving cars, including Google, Tesla and Ford, have obtained California DMV permits for 130 cars.

Uber opened up the self-driving car programme to San Francisco passengers on 14 December but has been testing the cars on the city's streets for more than a month.