Several protesters were injured by rubber bullets as thousands of municipal workers took to the streets on Monday to demand better pay, harassing hawkers and emptying refuse bins.

In Plettenberg Bay, Western Cape Police said eight "unruly" protesters and four police officers were injured during a strike.

Captain Malcolm Pojie said police used rubber bullets and pepper spray to disperse a group of about 100 SA Municipal Workers Union (Samwu) members when they began throwing rubbish and other items at passing motorists.

"Police intervened and protesters then began assaulting police officers by throwing stones at them. They had to retaliate."

Two people were arrested for public violence.

Limpopo police said three people were injured in Polokwane when some workers turned violent during a march to municipal offices.

Superintendent Moatshe Ngoepe said police fired rubber bullets into the crowd.

"They damaged the gate of the municipal entrance and they took all the dustbins and threw it [the rubbish] all around the streets. We intervened and during the process three people were slightly injured."

Ngoepe said reports that one of the injured had not been part of the protest would be investigated.

Twenty-five people were arrested on charges of public violence, malicious damage to property and organising an illegal gathering.

In Empangeni, KwaZulu-Natal police took 50 striking municipal workers in for questioning after they allegedly tried to set a police van alight.

"They threw a burning object, but the car was not destroyed," said Inspector Mbongeni Mdlalose.

In Pretoria, union officials prevented some marchers from stealing from hawkers next to the road.

Meanwhile the SA Municipal Workers' Union said the strike would continue until at least Wednesday.

"We are in the process of getting mandates from our members across the country on a new offer, which was the outcome of protracted negotiations between the parties over the weekend," Samwu said in a statement.

"These discussions will continue until Wednesday, when a national executive committee will convene to assess the strike and determine a way forward."

The union said its members came out in "full force" on Monday in support of the strike.

"Our structures report massive support for the strike, with many services, such as refuse removal, traffic, water maintenance, revenue collection not operating."

It said members were present in all major cities, as well as smaller municipalities like Bredasdorp, Mossel Bay and Beaufort West.

The union said the strike was conducted in a "peaceful and disciplined manner" and said it was "outraged" at reports of police action in Polokwane.

The main marches in Johannesburg, Cape Town and Durban proceeded, on the whole, peacefully.

The Cape Town municipality said extra law enforcement was sent to Khayelitsha, Killarney and Nyanga townships following reports of assault and intimidation by strikers.

Spokesperson Kylie Hatton said a law enforcement officer was assaulted at the Nyanga terminus by striking workers and later taken to a clinic for treatment.

The SA Local Government Association (Salga) called on unions to return to the negotiating table, saying it had already "significantly" upped its wage offer from 10.5 percent to 13 percent. Unions wanted 15 percent.

"Salga believes that negotiations are the most preferred vehicle to nurture industrial action (sic) since this is a critical prerequisite for quality service delivery and development," Salga executive director of labour relations, Mzwanele Yawa, said.

However, unions, including Samwu and the Independent Municipal and Allied Trade Union, which collectively represent 150,000 people, insisted their demands be met to ensure workers could cope with inflation, which peaked at 13.7 percent last year.

In Pretoria, Samwu's national general secretary Mthandeki Nhlapo said workers did not want a "starving wage", but one that would improve their lives.

"This is an insult to the workers, President Zuma must intervene... We did not vote to change the lives of a few selected, we voted for a better life for all."

A water services employee in central Johannesburg said: "We need more money with inflation everywhere."

Also present at the march was Samwu spokesperson Dumisani Langa who claimed that 70 percent of municipal workers were earning less than the R5000 a month the unions were demanding as a minimum wage.

"Nowadays you can't have a person making R3000 a month as a permanent employee," he said.