The major churches in South Africa are accusing the country's government of immoral action in proposed changes to the law on road tolls saying it unfairly hits poorer people.

South African lawmakers are working on changing the law on road tolls to allow for the electronic collection of tolls and the prosecution of those who fail to pay.

But the South African Council of Churches and the Southern African [Catholic] Bishops' Conference have joined the country's largest trade union umbrella in joining protests against a proposed system of electronic tolling on highways.

The provincial secretary of the Congress of South Trade Unions in Gauteng province, the most industrialized part of South Africa, Dumisani Dakile, said the system was "unfair" especially to the poor and the working class.

Dakile said they would be joined by at least 10 civil society bodies and some religious leaders in a series of protests in the next few weeks against the e-tolling of highways in Gauteng province.

The union leader said protesters would occupy all lanes on the highways but emergency lanes would remain open.

"Existing freeways, which serve as the main arterial routes within the economic hub of our country, have been appropriated to create toll roads, while no viable alternative routes exist," said the Bishop Abel Gabuza of Kimberley and Bishop Kevin Dowling of Rustenburg in a statement on behalf of the Catholic bishops.

"This is a serious abdication of government responsibility for public property."

The government says that charging tolls is the only viable way to pay for the maintenance of the country's highway system.

The transport department spokesperson, Tiyani Rikhotso, said the transport department was taken aback by the Catholic bishops stance.

"While we are taken aback by the SACBC position, the department remains committed to meeting with stakeholders, including the religious community, to clarify its intentions regarding the introduction of e-tolling in Gauteng," he said.

"[The] government, through the inter-ministerial committee, consulted with various stakeholders including the National Inter-Faith Leaders Council, South African Council of Churches, Cosatu, Road Freight Association and the South African Vehicle Rental and Leasing Association, which also made representations in Parliament."

Still the massive hikes in the costs of the road upgrades that led to the toll system "indicate that some serious investigations need to be initiated regarding possible corruption or price-fixing," the bishops said.

Father Michael Deeb, of the Catholic bishops' conference told journalists, people had questioned why the church was getting involved in the matter.

"After listening to things that have been going on for the last couple of years... we hoped the government would listen to the many reasonable arguments why e-tolls should be scrapped," Deeb said.

The protests would culminate in a provincial "stay-away" and march in June.

The battle inside the corridors of power is also still continuing, with discussions on the Transport Laws and Related Matters Amendment Bill, which was put on ice following proposed amendments by the African National Congress (ANC), which has ruled South Africa for 19 years.