China's government is pushing to raise the country's profile in global shipping and last year merged two state-owned firms to form COSCO Shipping, aiming to challenge the dominance of top players Maersk Line and Switzerland's MSC.
COSCO lifted 5.49 million TEU (20-foot container units) in the third quarter, up 23 percent from the same period last year, surpassing Maersk's 5.26 million TEU, according to the Alphaliner data, which was published this week.
It was unclear how much of COSCO's activity related to inter-Chinese trade.
The fall in the number of containers handled by Maersk in the quarter, which was down 2.4 percent from the same period last year, was partly due to a costly cyber attack that hit its shipping and port operations in July and August.