United Transport and Allied Trade Union (Utatu) members have rejected a Transnet wage-increase offer of 11%, and have elected to embark on an indefinite strike against that company.
"We, Utatu, are now officially on strike action," said Louis Brockett on Tuesday, deputy general secretary of Utatu, adding that 95% of its members rejected Transnet's offer.
He said its strike action will take off formally at 6am on Wednesday.
Utatu rejoins the South African Transport and Allied Workers' Union (Satawu) after it earlier halted industrial action to review Transnet's increased offer of 11% over the weekend. Initially, Transnet had offered 8%, whereas the two unions demanded 15% across the board.
Satawu's members have been on strike since Monday, and together the unions make up 85% of the about 50 000 Transnet workers now on strike.
Policy research officer at Satawu Jane Barrett said Utatu's decision "means that the strike will be absolutely solid, we expect that by tonight [Tuesday] Transnet operations will have completely shut down".