Transport minister Mable Chan said on Wednesday that officials will look into licensing requirements when the government extends the use of self-driving vehicles for online ride-hailing services.

Last Friday, the government announced in its transport strategy blueprint that it plans to promote the commercial use of autonomous cars in an orderly manner.

At a transport panel meeting at the legislature, Election Committee lawmaker Chan Siu-hung asked about the scope of these vehicles for car-hailing services.

The secretary replied that a dedicated group of transport officials will study the commercial licensing requirements for autonomous cars.

The lawmaker was also concerned about under what conditions the government would remove the "safety drivers" currently used as a back up in autonomous vehicles.

The minister said officials will talk to operators to ensure safety when they do without such drivers, stressing that their absence will not mean that things go unmanaged.

"We now have a safety driver on autonomous vehicles because we want to ensure that nothing would go wrong," she said.

"When we implement the commercial use of self-driving vehicles for the Airportcity Link this year, we hope there won't be a safety driver. We hope to achieve the same this year in Tung Chung and Kai Tak."

Many lawmakers also asked about the feasibility of building a fourth cross-harbour tunnel, after the government mentioned in the blueprint the need to expand capacity for cross-harbour traffic.

The DAB's Ben Chan asked for a timetable, and the minister replied that officials will look into existing public proposals and study the idea in a stringent manner.

"This is... a critically important phase for the future. We must conduct research in different phases over demands, matching demographic and economic developments, and the actual land requirements for roads," the transport chief said.

"[We have to see] how to achieve cost-effective solutions within resource constraints and financing packages, thereby establishing priorities."

The government also said that within six months, it plans to expand the scheme allowing vehicles from different Guangdong cities to be driven in Hong Kong.

The Southbound Travel Scheme currently covers four cities - Guangzhou, Zhuhai, Jiangmen and Zhongshan.

The minister said officials will study feedback from local businesses and drivers to determine the way forward.