Airport Authority Hong Kong, operator of the world's busiest cargo airport, says it needs a third runway to keep pace with the rapid growth in air traffic. The airport's two existing runways are forecast to reach capacity by 2020.

"The executive council has approved in principal the airport authority's recommendation to adopt the three-runway system as the future development option for its next stage of planning," Secretary for Transport and Housing Eva Cheng said.

The government-owned airport authority is now clear to start work on detailed design, financing, and an environment impact assessment, tasks which are expected to take about two years, she said.

Hong Kong overtook Memphis in 2010 as the world's busiest air cargo hub as a result of strong import and export growth in China, especially the Pearl River Delta region. The airport ranked third worldwide in terms of international passenger flows in 2010, behind London Heathrow and Paris Charles de Gaulle.

A public survey conducted by the University of Hong Kong last year said 73 percent of respondents favoured a third runway, but also showed concern that environmental impacts had not been fully addressed.

The third runway, on which construction was expected to start in 2014 at the earliest, Cheng said, and will take about eight years to build.

(Reporting by Alison Leung and Twinne Siu; Editing by Daniel Magnowski)

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