Two Hong Kong ferry operators have taken the wraps off new green-friendly vessels for six routes serving the outlying islands.

Three of the ships will set sail next month, with 19 more due to arrive by next year.

Speaking on Tuesday at the launch event for the three newly arrived vessels, Secretary for Transport and Logistics, Lam Sai-hung, said the 22 ferries will produce less pollution, featuring diesel engines which are more environmentally friendly.

"The design of the new ferries is eco-friendly. They are made of lighter materials, such as carbon fibre or aluminium alloys, to minimise the weight of the vessels. They also use an eco-friendly engine that meets the third level under the standard set by the International Maritime Organisation. These can reduce the emissions of nitrogen oxide," he explained.

The government is putting up HK$3 billion to support the purchases by operators Sun Ferry and Hong Kong and Kowloon Ferry.

The new vessels have a seating capacity of up to 500 passengers, featuring amenities such as a pet-friendly zone, lactation rooms, and a larger designated area for wheelchair users.