Transport Commissioner Rosanna Law said the government will decide when to extend the electronic tunnel toll system, or the HKeToll, to the three cross-harbour tunnels after its implementation at Lion Rock Tunnel on Sunday.

"We still need to look at Lion Rock Tunnel... how this comparatively-busy tunnel will do after the implementation of the e-toll system. Then, we will decide the second phase... the three cross-harbour tunnels... which one to go first and when," Law said

Both the Tsing Sha control area and Shing Mun tunnels are now using the HKeToll system, which is handling more than 110,000 vehicles a day.

The system, which allows motorists to drive through tunnels without having to stop to pay, will be in place at Lion Rock Tunnel from 5am on Sunday.

Law said she expects things to go smoothly at the tunnel, which has an average of 90,000 users a day.

740,000 cars now have the HKeToll tag – accounting for around 91 percent of vehicles in Hong Kong.