The City of Johannesburg has denied reports that a strike by Emergency Management Services (EMS) staff was because of maladministration and corruption.

"The city calls on workers with legitimate grievances or evidence of alleged corruption to present it to the city so that it can be investigated," spokesperson Gabu Tugwana said in a statement on Tuesday.

"The door is also open to the South African Municipal Workers' Union (Samwu) to produce such evidence, if it is available."

He said the city could not recklessly suspend any employees without any tangible evidence of misconduct and due process being followed.

"Bona fide complaints received through the appropriate channels will receive attention from the city," said Tugwana.

"If they are of a serious nature, [and] cannot be dealt with through existing channels, the city will consider the appointment of an independent person to investigate such complaints."

On Friday, Samwu announced that about 700 EMS workers would down tools to demonstrate their dissatisfaction with the acting head of the EMS, Tshepo Makola.

The union said workers alleged Makola had claimed a R100 000 overtime bonus while, as senior management, he was not entitled to overtime.

The claim was tantamount to corruption, Samwu said.

It had a minimum service level agreement with the EMS, which allowed a certain number of workers to strike despite the fact that EMS was an essential service.

The strike was scheduled to begin on Monday.

However, city spokesperson Nthatisi Modingoane said all staff reported to work on Monday morning.

Samwu' secretary Dumisani Langa said about 200 workers participated in the strike.

Modingoane rejected this number as "quite an exaggeration".

He had heard of about 40 people gathering outside Florida fire station, on the West Rand, and intimidating those who arrived for work.

Modingoane said the strikers were staff who were not scheduled to be at work on Monday morning.

Tugwana said Makola's car was also attacked and damaged near the fire station on Monday.

"It is also clear that the current strike does not enjoy universal support among all EMS employees," he said.

"Many of those committed to continue doing their work have complained that they are facing severe intimidation from those participating in the strike."