A new law requiring child car seats or other extra restraints to be fitted in private vehicles carrying children would be too difficult to implement on public transport, the government said on Tuesday.
From November, child restraining devices must be used in private cars for children under eight, unless they are at least 1.35 metres tall.
A chief engineer at the Transport Department, Eddy Wu, said half of traffic accidents affecting under eights involve private cars.
He added that it would be difficult for public transport operators to install restraining devices to suit all child passengers.
"Children of different ages require different kinds of restraints. For example, older children only need a booster seat, while infants need a baby car seat," he said.
"If public transport operators also had to offer suitable devices for children of different ages, or offer a certain quantity, it might create obstacles for their daily operations."
Wu also explained why children at least 1.35 metres tall will not need extra restraints. He said this is because their feet will touch the floor and an adult seatbelt would not cut into their necks.