Speaking after the firm's annual general meeting yesterday, China Merchant's vice-chairman, Li Jianhong, said it would be problematic if throughput slowed further in the third quarter.

Hong Kong container trade contracted 10.5 per cent year on year in May after a 12.2 per cent contraction in April, partly because of a strike by dock workers.

"The biggest uncertainty is volatility in mainland port volumes," said deputy managing director Zheng Shaoping.

Some think recent port throughput figures were skewed by fabrications that boosted cargo growth figures. Exporters may have faked trade by trucking goods to bonded warehouses in order to receive tax rebates. Goods in bonded warehouses are considered to have already passed through customs.

Li said he had noticed some fabrication of exports but that bonded warehouses had followed the law.

In the first five months, China Merchants handled 9.2 per cent more container cargo than a year earlier, boosted by ports in northern and eastern regions. Throughput at its Western Shenzhen port dropped 2 per cent year on year in the first five months.

The company is pinning its hopes on its overseas ports, including those in Sri Lanka and Nigeria.

"We think the new ports will offset the slowdown in the mainland," Li said, adding that their throughput would increase 10 per cent this year. The firm expects throughput at its overseas ports to rise to 30 per cent of the firm's total throughout within a few years from its current 10 per cent.

The firm is eyeing further acquisitions. It bought port assets from French shipping company CMA CGM in December last year. It has also purchased ports in the African country of Djibouti.