TAIPEI (Dow Jones) – A large number of new container ships due for delivery this year and next, and the possible return to service of idled vessels could extend industry oversupply into 2011, Bronson Hsieh, the chairman of Evergreen Marine Corp., said.

Container shipping line operators have posted large losses since the end of 2008 following the onset of the financial crisis, prompting them to scrap old vessels and idle some of their fleet. Those moves, coupled with improvements in the global economy, have helped freight rates to rise recently.

Speaking at an industry event in Taipei, Hsieh said the recent increases in freight rates would help the industry narrow its losses in the second half from the first half, but he warned oversupply remains a concern.

This year, 286 ships with a capacity of 8,000 twenty-foot equivalent units and above will join the global container fleet, while another 211 ships of this size will enter service next year, Hsieh said.

"And there over 500 redundant ships, anchored outside ports, waiting to re-enter (service)," he said. "The industry may return to normal perhaps in 2012."

AXS Alphaliner, a shipping consultancy, says about 10% of the global container fleet was idled at the end of September.

Evergreen Marine, the world's fourth-largest container line by capacity, has said it aims to reduce its fleet size by about 17% through 2013 by scrapping vessels and returning chartered ships to their owners.

Macquarie said in a report Wednesday that September marked the seasonal high for container volumes in Asia.

"We expect container pricing gains to decelerate and any reduction in operating loss to come from cost cutting," Macquarie analysts wrote.