Johannesburg - Striking South African state workers staged a protest march on Thursday after rejecting a revised wage offer aimed at ending their three-week strike that has the government and the labour movement at loggerheads.

The majority of unions, most of which are in the largest labour federation COSATU, voted against the offer on Wednesday, prolonging a strike by 1.3 million state workers that a prominent economist said was costing about $150 million a day.

The strike has shut schools, led to bodies piling up in state morgues and thrown cold water on the national euphoria over hosting the June-July football World Cup. It also has dampened investor sentiment for Africa's biggest economy.

The government has said it cannot afford the offer it has on the table, let alone anything higher, and will have to make cuts elsewhere to meet it.

A formal bargaining session between labour and government officials planned for Thursday will now likely to take place on Monday as unions seek more time to persuade their rank-and-file members to reconsider the offer, officials said.

Hundreds of striking state workers dressed in red T-shirts, sang and shouted in a protest march through the streets of Johannesburg, calling on government to meet their demands.