“The intimidation of drivers and depot staff has seen certain regions becoming no-go zones,” said Avhapfani Tshifularo, executive director of the South African Petroleum Industry Association (Sapia).
He said intimidation has disrupted fuel deliveries resulting in low stock levels, and that some retail sites were running dry.
“The safety of drivers and employees remains paramount and all necessary steps are being taken by the petroleum companies to protect their staff,” said Tshifularo.
The four striking freight unions were expected to announce their decision on a revised wage offer on Friday.
The Road Freight Employers' Association (RFEA) has tabled a 9% increase across the board for 2011 and 8.5% for the second year.
The unions - the Transport and Allied Workers Union of SA, the Professional Transport Workers Union, SA Transport and Allied Workers' Union, and the Motor Transport Workers Union - initially demanded a 10% pay rise for 2011 and 10% for 2012.
The RFEA initially offered 7.5% for 2011 and again in 2012.
Incidents of intimidation have been reported throughout the week with non-striking truckers beaten and their trucks looted and burnt.
More than 20 trucks have been damaged, 16 people injured and 32 arrested.
“Petroleum companies have put contingency plans in place; however, due to the violent nature of the strike, activation of these contingency plans is not always possible,” Tshifularo said.
Police should act against those who were guilty of intimidation and violence in the transport workers' strike, the SA Chamber of Commerce and Industry (Sacci) said on Friday.
"A number of Sacci members have confirmed that unrest, intimidation and violence has taken place nationwide. These incidents impinge on the constitutional rights of society to a safe environment," Sacci president Chose Choeu said.