A Hapag-Lloyd boxship lost some of its cargo in rough seas before releasing fuel-oil Thursday into a container port off New York City's Staten Island, an offical said Saturday.

The 4,121-teu Dublin Express (built 2002) dropped 16 containers in stormy weather Thursday while sailing from Florida's Port Everglades to New York City's Staten Island.

The company said Friday the ship spilled oil from a 40-centimetre hole in its hull Thursday evening while unloading boxes at Global Marine New York Container Terminal.

"During the storm we lost 16 containers, but we don’t know yet if the loss of the containers is related to the leak of the ship," spokesman Nils Haupt told TradeWinds.

"Investigations continue."

Haupt did not say where the storm occurred or how severe it was.

The hull opening was sealed during the night and containment booms were set up to prevent additional spreading of the fuel to protect nearby nature reserves, the company said.

"The cause is not clear yet; it is under investigation," Haupt said.

"We also don’t know the exact amount of oil yet, still awaiting reports from the respective authorities."

Hapag-Lloyd said the ship had encountered heavy swells while sailing from Port Everglades to New York.

The company hired Gallagher Marine Services to provide a "qualified individual" to handle the spill cleanup.

"It is still too early to make an accurate assessment of the damage," Hapag-Lloyd said.

"Hapag-Lloyd is working closely with the relevant authorities and interested parties to minimise the impact on people and the environment."

The US Coast Guard provided aerial assessment of the spill while city police responded to the scene.

Hamburg-based Hapag-Lloyd owns 222 containerships.