JOHANNESBURG - Truck drivers are threatening to shut down major highways around the country on Sunday.
They're upset over the employment of foreign nationals by local companies.
NATJOINTS -- which is made up of the police, defence force and State Security Agency -- is on standby.
It says it's mobilised all resources to prevent and combat any form of lawlessness.
READ: Truck driver protest | Clampdown on illegal foreign drivers
It's called on those taking part to do so peacefully.
There have previously been violent incidents at demonstrations over the same issue.