The Kiel Canal is expected to remain closed to shipping throughout Friday.
The duration of the oil fight depends, among other things, on the weather conditions, said the head of the emergency command, Robby Renner, on Thursday evening.
A particular challenge is the wind, which according to the forecast is expected to turn at times during the course of Friday.
According to Renner, the waterway and shipping office for the Kiel Canal, which gives the go-ahead for shipping, is currently assuming a blockage until at least 12 noon on Saturday.
The waterway was closed on Wednesday after large amounts of oil spilled due to a leak in a pipeline in the port of Brunsbüttel.
The emergency command had signaled on Thursday that the canal could be opened to traffic on Friday afternoon at the earliest.
Oil spill response work has progressed well on the canal and on the shore.
Three special ships were also used.
It was initially unclear why the leak in the pipeline had occurred.
Police investigations are ongoing.
The canal between Kiel on the Baltic Sea and Brunsbüttel (Dithmarschen district) at the mouth of the Elbe in the North Sea is the world's busiest artificial sea waterway.