If the strike proceeds, it is expected to severely hamper trade as one-third of the port operations are conducted outside of normal working hours.
Authorities in Hamburg have recently selected construction and property group Hochtief and Macquarie Bank of Australia as its preferred partners in privatisation talks that relate to the sale of a 49.9 per cent stake in Hamburger Hafen und Logistik (HHLA), which operates container and bulk-cargo piers, to German or Austrian investors.
Dubai Ports and German railway operator Deutsche Bahn have already been eliminated from the bidding process.
In response to the strike' threat, the city government has slammed union leaders for exaggerating the consequences of privatisation to port workers, giving assurances their concerns are "unjustified" and that the stock sale did not involve asset-stripping, a report by Deutsche Presse-Agentur said.
Authorities in Hamburg say a final decision will be made this spring on whether to sell the stake to private investors or to make an initial public offering of HHLA stock.