ECT, Europe's largest stevedoring company, said a strike could be imminent since it failed to reach agreement on a collective employment contract with its largest union, FNV.
The company did agree to terms with a smaller union, CNV, which accepted ECT's final offer. FNV will now consult its rank and file.
ECT said there is no room for a higher offer, and 'in view of the financial situation strikes will put ECT in the danger zone', according to a statement released by the company.
A privately-held unit of Hutchison Port Holdings, ECT is one of the largest container terminal operators in Europe, handling almost three quarters of all containers in the port of Rotterdam. In 1999, ECT handled a total of 4.5 million TEU. It employs 2,300 people.
ECT and its divisions operate several terminals on the Maasvlakte peninsula near the North Sea, and two new terminals, in Willebroek, Belgium and Duisburg, Germany.