The 82-metre barge Undine was severely damaged when four of her eight fuel tanks were torn open in the accident on the waterway near a rural district of Hamburg. Police are questioning both ship captains in an ongoing investigation of the incident.
Fire department workers laid out floating oil barriers and plan to drag the 10-kilometre oil slick to a dock in the port city, where it will be extracted from the water, a fire department spokesperson said.
River traffic remains closed during clean up operations. The damaged tanker has been moored in a sluice canal near Geesthacht.