Dutch manager Chemship has said the cause of a collision between one of its tankers and a passenger vessel is not yet known.

The 14,300-dwt Chemical Marketer (built 2004) and river cruiseship Viking Idun were damaged above the waterline on Monday in the Westerschelde in Terneuzen.

Chemship said that following the impact a number of passengers on Viking Idun suffered injuries and had received medical attention.