HONG Kong's government gave conditional approval yesterday to a third runway for the city's airport that will require massive land reclamation.

Transport Secretary Eva Cheng said government policy advisers approved an expansion plan for Chek Lap Kok airport that involves reclaiming 650 hectares of land from the sea. The project is expected to cost US$11 billion, including US$5 billion for the land reclamation.

The airport said the third runway is needed because by 2020 the two existing ones won't be able to accommodate more flights. Annual passenger numbers may nearly double to 97 million by 2030 from 53.9 million in 2011 while air cargo is expected to more than double to 8.9 million tons from 4 million tons in the same period.

Environmentalists worry about the project's impact on air quality and on endangered Chinese white dolphins found in the waters surrounding the airport on Lantau Island.