The Information Communication Technology Union has given media company Tiso Blackstar Group a 48-hour notice of its intention to strike over unresolved disputes relating to salaries and bonuses.
The notice was served on Friday, meaning ICTU intends to start industrial action from Monday morning.
Tiso Blackstar owns publications including the Sunday Times, Business Day and Financial Mail.
In its notice, the union said its strike was protected.
ICTU intends to hold go-slow demonstrations for the whole of next week, as well as a picket next Thursday, a national shutdown on May 6, and a march to Tiso Blackstar's headquarters on May 7.
Regarding the disputes over salaries and bonuses, the union said it was open to further discussion.
"We are further amenable to engage with Tiso Blackstar Group regarding these matters at your earliest convenient time to find solutions," the notice said.
ICTU president Moeketsi Lepheana told Fin24 that about 80% of Tiso Blackstar’s employees were represented by the union.