Johannesburg - Satawu on Monday issued secondary strike notices to several port-related companies, an official said.
Richards Bay Coal Terminal, Safmarine, AP Moller Maersk, Bidfreight Port Operations, Grindrod, Hazard Marine, Hermes Ship Chandlers, National Ship Chandlers and SA Container Depots were served with the notices, according to SA Transport and Allied Workers' Union general secretary Zenzo Mahlangu.
"Notices have also been issued on the former Transnet company, Arrivia.com as well as the motor ferry companies, Motorvia and Auto Carriers."
Should the strike by Transnet workers that began on May 10 not be resolved by June 1, sympathy strikes would be legal in these companies, he said in a statement.
Satawu further intended to issue secondary strike notices on the Road Freight Association, whose members are road hauliers, as well as on aviation companies including South African Airways.
The union further called for support from the International Transport Workers' Federation, which represents 751 trade unions with 4.6 million workers in 154 countries.
"Satawu believes that Transnet is holding the country to ransom with its intransigence. In the course of the two-week strike, they have to date not shifted their stance on the basic wage."
It was within Transnet's power to bring the strike to an end by "climbing out of their rigidity", Mahlangu claimed.
The United Transport and Allied Trade Union, which went on strike with Satawu, accepted the 11 percent offer on Friday. Satawu still wanted 15 percent.