But the Guangdong capital's transport infrastructure was expanding and its aspirations to be an international transport hub could not be denied forever. Hong Kong could find itself in second place as early as the middle of the next decade, Professor Zheng said.

Guangzhou's new Baiyun airport will start operations next year, and some of its equipment was more advanced than Hong Kong's Chek Lap Kok airport, said Professor Zheng, of Zhongshan University in Guangzhou.

However, he said Guangzhou's airport served 300 routes, of which only 100 were international, while Hong Kong served 500 air routes, of which 400 were international. And because Guangzhou's services were mainly domestic, many of the aircraft serving it were small or medium-sized, with less passenger or freight capacity than the flights serving Hong Kong. As a result, said Professor Zheng, Hong Kong's efficiency in air freight and passenger capacity outweighed Guangzhou's.

On seaports, Guangzhou's Nansha port focuses on the shipment of bulk cargo, raw materials and commodities like oil and timber, and only 30 per cent of its freight is international. By contrast, Hong Kong's port is more diversified and international. Hence the two ports could complement each other.

But he also said that Guangzhou's aspirations to be an international transport hub could not be contained. If Hong Kong were to lose its position as China's leading air and sea port, its logistics and tourism businesses would suffer, he said, and that would be bad for Hong Kong.

'I believe Hong Kong's role as the number one port must be maintained,' he said, suggesting the city needed to stay on its toes.

Offering a contrary opinion, Michael Enright of the University of Hong Kong argued that the loss of pole position need not spell the end of Hong Kong.

He said London and New York outsourced their port operations yet remained important cities.