A new wage settlement for striking Western Cape farm workers must be found immediately, Cosatu General Secretary Zwelinzima Vavi said on Wednesday.

"There is an urgent need to reach an agreement on a new minimum wage to address workers' demand for R150 a day before December 4," he told reporters in Johannesburg.

Workers have agreed to suspend their strike until December 4, on condition that the employment condition commission (ECC) look at the sectoral determination, including the minimum wage, for agriculture.

Vavi said that while the ECC was urgently considering an increase to the minimum wage for farm workers, an increase was still unlikely to be made official until early next year.

"This should not, however, prevent employers in the meantime from agreeing to a wage increase, since the sectoral determination sets minimum wages. There is nothing to stop employers paying more, as some already do," he said.

Vavi said farm employers were being "uncooperative" and some were using private security companies.

"There is a danger of the situation getting out of everyone's control."

Cosatu President Sidumo Dlamini said it had struggled to unionise farms, with only about five percent of an estimated million farm workers now union members.

He said this was because of the situation in the farming sector, where some farmers were "hell-bent on a pre-democracy mode of thinking".

This included limiting workers' rights, refusing to pay a living wage, and the continued use of the "tot system" -- offering alcohol as payment.

Dlamini said there were structural reasons why Cosatu had had difficulty unionising farm workers, including the seasonal nature of their work.

"That doesn't give us an excuse. This is the most vulnerable sector of South African workers."

He said Cosatu would seek ways to help its affiliate, the Food and Allied Workers' Union, to improve its ability to reach out and register farm workers as union members.

Vavi said one of the issues Cosatu was considering was how to keep farm workers in the union year-round when their work was seasonal.

This would require it to renew old debates about farm workers and follow through on them.

"We have been forced now to go back to the discussions that have happened in the federation over many years, but we have not taken those discussions to their conclusions," Vavi said.

Sixteen Western Cape towns have been hit by violent protests this month over farming wages and working conditions. Two people have died and there has been extensive damage to property.

The protests started with table grape harvesters in De Doorns, who were calling for wages of R150 a day. Most earn between R69 and R75 a day.