Maersk said attempts to make the current round of mid-December rate increases stick is hard because of the lack of shippers in the market, Reuters reported.

David Williams, company's head of east and central China, told Reuters that attempts to raise rates were already under pressure.

The company, which levied a $900 per TEU increase in November, has been trying to curb losses as too many big ships chase too few customers.

"We had an increase again on Monday, on December 15, pushing the spot rates up to $2,600 per FEU but we've already seen that come under pressure in the current week," said Mr Williams.

"So the rate market remains extremely volatile and that's one of the challenges that we have as an industry - success or failure depends on supply and demand," he said.

Mr Williams said that its 2M shipping alliance with Mediterranean Shipping Co (MSC) would be ready to operate next month. The first sailing is scheduled for January 15 from Ningbo Port.