The Airport Authority said on Monday it has suspended the use of autonomous buses within the airport area.

The suspension came after a collision between two buses used to carry staff in the airport's restricted area on Sunday afternoon.

A spokesman said there were no passengers on board at the time and no injuries caused.

He added that the incident did not disrupt overall airport operations.

In response to media enquiries, the authority said the collision happened in a more complicated road section within the airport's restricted area.

Preliminary investigations showed that the two buses' safety systems were working and controlled the vehicle speed at an extremely slow pace, which the authority said means they were travelling below 5 km/h.

It also said it has urged the company behind the driverless technology to submit a detailed report.

An electronic engineering specialist said autonomous buses are typically equipped with sensors and cameras for obstacle detection.

Tsang Kim-fung, who formerly chaired the “Internet of Things” Committee of the Smart City Consortium, listed a few possible causes of the collision.

"First, it's sensor malfunctions or misreading of the environment," he said.

"Second, there could be software error in interpreting traffic rules or the right of way.

"And the third can be a communications breakdown between the two buses or with a central control system."

Tsang, a spokesman for the Hong Kong Institution of Engineers' electronics division, also urged the authority to conduct thorough safety checks before resuming the driverless bus operations.

"Number one, this is in the form of full system diagnostics, including software, first of all, and possibly hardware updates," he said.

"And secondly, they should calibrate or recalibrate the sensors and then validate the obstacle detection."

The authority also needs to run controlled tests, update training protocols for remote operators, as well as to be certified by a third party, Tsang added.