Adelaide Port workers who struck on Thursday got the support of the International Transport Federation (ITF) in their ongoing labor row with port operator DP World. The ITF spoke against the lockout of employees.

"The ITF wholly condemns the practice of locking out workers. This is not an acceptable course of action, particularly from a global employer that values its commitment to our people and our customers. DPW's current position is not only harmful to its customers, but is damaging negotiations," ITF Dockers' Section Secretary Frank Leys said in statement on Thursday.

"The ITF strongly urges the company to withdraw the lockout notice and engage in meaningful dialogue in order to achieve a negotiated settlement acceptable to all parties. Anything less could seriously damage its relations with its workforce worldwide, as well as its image as a company to do business with," Mr Leys added.

The strike was the result of an impasse between DP World and the Maritime Union of Australia which had been negotiating the pay and work conditions of port employees for the past eight months. The workers asked for an annual pay rise of 5 per cent. They also aired concern over work safety and the hiring of more casual workers.

The casual workers are handling as much or more than their permanent employees even if DP World has the capacity to make the casual workers.

Finders Ports, which holds a 40 per cent stake in DP World operations, lamented that because of the industrial action importers and exporters in South Australia are suffering from slower processing of documents. Business, though, have the option to instead send their containers by rail to Melbourne but it would jack up their cost.

Federal Workplace Relations Minister Bill Shorten declined to intervene this time in the industrial row between DP World and the union. He pointed out that no one at the current stage has indicated they want arbitration so he would leave the two parties to negotiate.

Mr Leys said dockers in different parts of the world are ready to show their solidarity with their Australian counterparts.