Police are on high alert nationally amid threats of a national shutdown on Friday, and a spokesperson says law enforcement officers have been deployed to "prevent and combat any forms of criminality".

In a statement, the police said they were aware of "unsigned messages and posters circulating on various social media platforms calling for a national shutdown".

"Those behind these messages are warned and reminded that prohibiting people's freedom of movement is a criminal offence. Members of the public are therefore cautioned against spreading such messages that seek to mobilise communities to respond to the shutdown," National police spokesperson Colonel Athlenda Mathe said.

Mathe said the National Joint Operational and Intelligence Structure (NatJoints) met on Wednesday for a briefing by the Intelligence Coordinating Committee on the credibility of the calls for a national shutdown.

"The intelligence community is closely monitoring the situation and the associated risks. With this said, law enforcement officers have been deployed and are on high alert to prevent and combat any forms of criminality," said Mathe.

The protests are reportedly linked to the recent spike in fuel prices and associated increases in taxi fares.

Petrol prices increased by R2.43 per litre last week. The cost of diesel climbed by more than R1 a litre.

The shutdown also sparked calls for school closures, but Department of Basic Education spokesperson Elijah Mhlanga said the department would proceed with normal schooling on Friday.

He said the department was aware of the reports of a shutdown.

"We trust that the law enforcement agencies will do their work to manage the situation," he said.

Meanwhile, two taxi associations – the South African National Taxi Council (Santaco) and the National Taxi Alliance – have been linked to the national protest action. However, both associations have distanced themselves from the shutdown rumours.

Santaco chief strategic manager Bafana Magagula was not available for comment at the time of publication.

However, the organisation said on social media that it would not be part of any mass action on Friday.

"Santaco has never lobbied any organisation for a national shutdown and is not even planning any shutdown. We still, however, hold the strongest view that there's an urgent intervention needed from [government], and this despite looming taxi fare increases," the organisation said in a tweet.

National Taxi Alliance spokesperson Theo Malele said the organisation would not participate in any protest action.

"We first want to ensure that we've exhausted all avenues of dialogue with the government. Only if that fails will we look at forging ahead with like-minded businesses and civil society groups to plan a national shutdown. We don't know who is planning Friday's shutdown," Malele added.

Malele said the organisation was forced to consider an increase in taxi fares due to rising fuel costs, and this was likely to be made public within the next three weeks.

"It's most unfortunate but we now finally have to increase fares. We've been forced to increase fares by circumstances beyond us. Some members of the industry are losing their cars because they can't meet their financial obligations, directly because of pressures of fuel prices skyrocketing," he added.

In a statement, the KwaZulu-Natal Department of Transport welcomed the decision by the taxi industry not to participate in the shutdown.

The department said the taxi industry had agreed on an urgent engagement with the government to find measures to mitigate the impact of ongoing petrol price hikes on their operations.

The meeting is expected to take place on Friday.

Labour union Cosatu was also linked to the protest but said it had no plans to embark on any mass action.

"Cosatu would need to engage affiliates for a mandate. Affiliates would have to engage members and workers to receive a mandate. Workers would need to be balloted. A Section 77 certificate would need to be a...