Petrol tanker drivers were not on strike, but may join the action "if called upon" to do so, the South African Transport and Allied Workers' Union (Satawu) said on Thursday.

"As far as we know our members are working. Due to the current strike, our petrol tanker drivers are directly affected," Satawu Rea Molopyane said.

"We call on employers to practise caution and not endanger the lives of our members. Appropriate measures should be taken for the protection of the non-striking drivers.

"We will, however, mobilise solidarity support if called upon, including marches and pickets, with the striking members of Ceppwawu should their wage demands go unmet."

Fuel workers from the Chemical, Energy, Paper, Printing, Wood, and Allied Workers Union (Ceppwawu), the Allied Workers Union, and the General Industries Workers Union of SA downed tools on Monday, demanding a minimum salary of R6 000 a month and a 40-hour working week.

The strike has caused fuel shortages at petrol stations in Gauteng and KwaZulu-Natal.

Molopyane said the Fuel Retailers Association used around 300 trucks to transport fuel daily from Durban to Johannesburg.

The petroleum industry stood to lose "millions" if Satawu were to join the strike.

"Satawu Road Freight Sector has over 65,000 members, who if called upon will join in Ceppwawu in their fight for a decent living wage and bring the South African petroleum industry to its knees.

"Ceppwawu's demands are eminently reasonable, given the very low wages that workers earn. We agree with them in the context of the current economic climate," he said.

Satawu called on employers in the sector to table an improved offer as "quickly as possible".

Employers and unions in the petroleum sector have indicated a willingness to meet, the Bargaining Council for the Chemical Industry said.

"The council has proposed that both parties meet to open discussions for negotiations," said general secretary Ingrid Dimo.

"Both parties have yet to decide on it, but have indicated their willingness to meet."

A date would be set by the council once both parties had made their decisions.

"We are expecting them to meet over the weekend, or by latest next week," she said.

The proposal was made on Wednesday.

Mxolisi Ratsibe, chairman of the National Petroleum Employers Association (NPEA), said there was a breakdown in wage talks at the end of June, and that unions and employers had not met since.