"If the slick reaches Port Said it could damage ships' engines and quays," the official said. He added canal traffic had not been affected by the spill.

The official said it was not possible to say if the port would have to be closed if the slick reached it.

About 10,000 cubic metres of crude oil leaked from a Kuwaiti tanker on Tuesday after it collided with a quay in the canal.

Paul Horsman, a spokesman for environmental group Greenpeace, said the spill was "fairly large" but its presence in the enclosed space of the canal made a clean up easier.

"Every effort should be made, even if it means closing the canal, to stop the oil leaking out into the open sea where it could harm the environment and be more difficult to remove," Horsman told Reuters by telephone.

He added the authorities should use mechanical means to clean the spill and not chemicals, which would add pollutants to the water likely to leak into the Mediterranean where they could harm wildlife.