Public servants started an indefinite, countrywide strike on Wednesday to press for better wages, saying that their patience with the government has run out.

"We have been patiently trying to persuade the employer to present a revised offer," the Congress of South African Trade Unions (Cosatu) and the Independent labour Caucus (ILC) said in a joint statement late Tuesday.

"The strike for public service unions will continue until such time that the employer accedes to the demands of the workers."

Picketing will take place at "all our work stations" while mass marches were being planned across the country for August 26.

South African Democratic Teacher's Union (Sadtu) spokesperson Nomusa Cembi said that most of their 245 000 members were expected to take part in the strike.

Sadtu has urged striking teachers not to intimidate others, following reports of classroom disruptions in the Vaal Triangle in Gauteng earlier this week.

"There's no need to intimidate... Our members are keen to go on strike, they don't need to be intimidated to go on strike," said Cembi.

She said that no marches had been planned for Wednesday because there had not been enough time to organise marches.

"People will meet and discuss their plans... those who can manage to organise a march today [Wednesday], they will march.

"But we are not saying to teachers, 'be out on the streets', what we are saying is, 'stay away from work'."

The Western Cape Education MEC, Donald Grant, urged schoolchildren not to stay away from school.

"Our... objective is to ensure that learners continue to read, write and calculate. We urge parents to ensure that their children bring extra learning materials to school," said Grant.

Examples of such learning materials include library books, textbooks, crosswords and past examination papers.

"The department will, wherever possible, provide teaching alternatives and will ensure that as many resources are directed to our Grade 12 learners, who have 55 days to go till their first practical NSC [national senior certificate] examinations."

Grant said that the provincial department would do everything in its power to ensure that learners were safe.

Gauteng education MEC Barbara Creecy was scheduled to brief the media on contingency plans on Wednesday morning.

Public servant unions on Wednesday rejected the State's 7% salary increase and R700 a month housing allowance offer.

Its members were demanding an 8,6% increase with a monthly housing allowance of R1000.