Five Hong Kong Uber drivers arrested in a dramatic police swoop pleaded not guilty Wednesday to driving without proper licences.

The case comes as the burgeoning company encounters regulatory roadblocks around the world, and hit the headlines once more after an Uber driver in the United States allegedly went on a killing spree.

The August sting operation in Hong Kong came after furious cabbies in the southern Chinese city smashed up their own taxis with hammers and drove slowly towards the government headquarters, calling on authorities to act over unlicensed drivers.

All five drivers pleaded not guilty to “driving a motor vehicle for the carriage of passenger for hire or reward” without a proper licence, and driving without third-party insurance.

Defence lawyer Phillip Ross told the magistrates’ court he intends to seek a “stay of proceedings” for the drivers. The case was adjourned to March 23 for a pre-trial review.

Two other drivers arrested in the August swoop pleaded guilty to the same charges last month and were fined HK$7,000 ($900), with their driving licences revoked for 12 months.

Uber’s office in Cheung Sha Wan.

San Francisco-based Uber has expanded to hundreds of cities in at least 68 countries and is valued at more than $50 billion.

But traditional taxi drivers remain fiercely opposed, triggering a backlash including violent protests in Brazil where one driver was briefly kidnapped.

Taiwan said in August it had fined Uber a total US$1 million for improper registration over the preceding year.

The firm’s safety standards have also been called into question after Uber drivers were accused of abduction and sexual attacks on female passengers in India and the United States.

In the United States Monday Jason Brian Dalton, 45, was charged with six counts of murder after the shooting rampage in the state of Michigan.

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