Thousands of striking workers descended on the city from all directions this morning - as at least one clash was reported between municipal workers and Metro Police outside the civic centre .

As the crowds teemed in the streets, union officials frantically negotiated with police to authorise the planned march on Parliament .

One official feared "pandemonium" in the city centre if permission was not granted for the march.

The mass action began as the government accepted a proposal for a 7.25% wage increase for public servants, up from its 6.5% offer.

Demanding to see Mayor Helen Zille, about 60 SA Municipal Workers Union members barged through the glass doors on the station deck side of the building.

In Keizersgracht Street, thousands gathered for the planned mass march on Parliament.

The CBD was virtually deserted, with police officers and patrol vans out in full force.

Small businesses were closing down and street vendors packing up for fear of violence and looting.

At around 10.30am, protesters in T-shirts marked with the National Education, Health and Allied Workers logo forced Home Affairs in Barrack Street to shut down.

Security officers at the door said the strikers had demanded that they shut immediately "or that there would be trouble".

Although permission had been granted by authorities for striking workers to be transported into the city centre, unions had not been granted permission for a march.

By late morning there was a tense stand-off as union leaders negotiated with police for permission to stage the march.

"We are talking to the police now but the problem is that more and more people are arriving, and groups are coming from all over the city," said Suraya Jawoodeen, Nehawu's general secretary.

"The crowd is getting bigger and bigger and we're trying to find a way with the police to be allowed to move people on to Plein and Roeland streets.

"But we're concerned that there will be pandemonium, because we are not allowed to march at all," Jawoodeen told the Cape Argus.

Meanwhile education officials said hundreds of schools were closed with only a few schools operating on a skeleton staff.

Many principals have asked parents to keep their children at home for their own safety today.

Gert Witbooi, spokesman for Education MEC Cameron Dugmore, said a number of schools had told the department they would be closed today because of safety concerns.

Bellville South Secondary pupils were sent home this morning shortly after they arrived at school, after a group of public servants intimidated pupils at the school gate.

At Jan van Riebeeck High in the city centre, pupils will continue with exams - but principal Hammies van Niekerk said: "All our children are wearing civvies today.

"If there is any problem we will disperse them."

The provincial Health Department reported that its senior staff and SANDF personnel were helping out at health institutions worst affected by today's strike.

Several hundred people picketed this morning outside Groote Schuur and Tygerberg hospitals.

"At the three Khayelitsha clinics we have two military doctors and several nurses, as well as security people for the SANDF and no services have been closed," department spokeswoman Faiza Steyn said. "All our six doctors are at work at these clinics but 14 of the 34 nurses have stayed away today."

At Tygerberg, sixth-year medical students were helping to take care of patients in the wards, and SANDF personnel were being moved around to where they were most needed.

At Groote Schuur Hospital, scores of workers marched to the doors of wards this morning, calling out workers who were still on duty.

Singing, clapping and dancing, 500 went to the main entrance, the maternity centre, the old hospital building and even the maintenance buildings. Pickets blocked the hospital entrances.

Regional Justice head Hishaam Mohamed said there were no interpreters at the High Court today. Blue Downs, Kuils River and Atlantis magistrate's courts were affected and postponements were likely.

But there would no official closure of courts today, Mohamed said.

At the civic centre Samwu leaders exchanged harsh words with police, saying the city had not ordered a lockout and therefore could not stop unions from bringing workers to the city manager and the mayor.

The city's executive director for service delivery integration, Mike Marsden, said he would take the memorandum from Samwu outside the building and hand it to the city manager, but Samwu refused to accept this offer.

Shortly after 11am the city agreed to allow workers into the civic centre. Mayor Helen Zille was delayed in a meeting while the commotion went on downstairs.

The army deployed "large numbers" of troops countrywide to support police.

Amid reports that some military personnel were planning to embark on a sympathy strike today, army spokesman Colonel Sydney Zeeman said soldiers were prohibited from striking, and warned that transgressors faced harsh punishment.

"But we have deployed units nationwide in our traditional role of providing support for the police. It is a very big deployment," he said.

Cosatu's Western Cape secretary, Tony Ehrenreich, said the federation was hoping the widening action would impress on the government the need to respond.

The unions have rejected a mediated 7.25% offer, and are pushing for 10%, down from an initial demand for 12%.