Police Minister Senzo Mchunu says there are links between the so-called construction mafia and other forms of organised crime.
He was speaking at a national summit on crime at construction sites in Durban.
The summit has heard that the problem began in KwaZulu-Natal and has spread to Gauteng, the Western Cape and the Eastern Cape.
It takes the form of site invasions, intimidating contractors on site and extorting protection money.
Mchunu has encouraged contractors to report these crimes.
