Cape Town: Thousands of striking public service workers gathered for rallies in major cities across South Africa on Thursday to press their claims for higher wages on the ninth day of a crippling strike.

The rallies were scheduled as unions representing over a million workers, who declared an indefinite strike on August 18, threatened to broaden the strike into a total industrial shutdown.

"We are expecting thousands and thousands of people," said teachers' union general secretary Mugwena Maluleke in Johannesburg.

The marches were a message to the government to bring a revised wage offer to unions, said Maluleke, who estimated that nearly 800,000 workers had joined the strike.

"If the government does not do that, this strike will continue. The unions are not willing to back down."

The country's largest trade union federation Cosatu has called on all of its affiliates - which include unions in key mining and manufacturing sectors - to strike in solidarity with public servants if their demands are not met.

The public sector strike has severely hit schools and hospitals with army medics mobilised to support skeleton staff.

Unions are insisting on an 8.6 percent increase and a 1,000-rand (137-dollar, 107-euro) housing allowance. The government, which has offered a seven percent rise and a 700 rand allowance, said it cannot afford the union demands.