AP Moller-Maersk chief executive Vincent Clerc is warning of more delays and port congestion due to a sudden spate of orders by retailers stocking up for Christmas.

The Danish container line’s boss told the Financial Times that shipping costs have seen an “almost vertical” increase over the past few weeks.

This is due to congestion growing at Asian and Middle Eastern terminals, which could in turn prompt more clients to ship goods earlier than normal, he said.