South Africa will soon collect tolls on highways in Gauteng, the densely populated province that includes Johannesburg and Pretoria, the finance minister said Wednesday despite public outcry.

"I am mindful that the introduction of tolling to finance the Gauteng Freeway Improvement Programme has caused considerable public reaction," Minister Pravin Gordhan said in his annual budget speech.

In a bid to lower motorists' toll burden, Gordhan said the government would kick in an extra 5.8 billion rand ($750 million) toward the 20 billion rand in loans the national road agency has taken out to upgrade and expand highways around capital city Pretoria and economic hub Johannesburg.

But despite vehement objections by drivers since toll rates were published in February last year, the government said in a separate announcement that tolling would begin on April 30.

Cars will pay 0.3 rand per kilometre, down from the 0.49 rand initially announced.