President Jacob Zuma is already facing an official investigation over the multi-million dollar renovation of his homestead in KwaZulu Natal.
It and a proposed building of a nearby town has been dubbed "Zumaville".
Provincial authorities have said the road development plan preceded Mr Zuma's presidency.
But the Democratic Alliance has questioned why so much emphasis is being placed on this area of South Africa.
The BBC's Pumza Fihlani, in Johannesburg, says many development plans and road upgrades across the country, some of which are urgently needed, never get off the ground often because of lack of finance or corrupt tenders.
On Sunday, it was revealed that South Africa's Public Protector Thuli Madonsela had opened an investigation into the publicly funded construction of Mr Zuma's private residence in the district of Nkandla.
The chalets and state of the art security are said to have cost $27m (£17m).
The unveiling by the KwaZulu Natal government of two new nearby road networks, costing $67m, happened two days later.
The Democratic Alliance's Ian Ollis said that he would request that Ms Madonsela extend her investigation to include the road upgrades leading to Mr Zuma's homestead.
"KwaZulu Natal certainly has enough road and transport infrastructure projects which could have been considered as alternatives to the Nkandla projects," Mr Ollis said.
But KwaZulu Natal's Transport Minister Willies Mchunu said the road project was above board and various villages had been marked for development before Mr Zuma came to power in 2009.
"In fact, former President Thabo Mbeki identified Nkandla and Msinga as priority areas needing development. This has nothing to do with President Zuma," South Africa's Mercury newspaper quoted him as saying.
In recent months, there has also been controversy over proposals for a town to be built about 3km (two miles) from Mr Zuma's Nkandla homestead.
"Public funds should not be spent to service the home and the hometown of the president to the detriment of other projects that are meant to improve the lives of ordinary South Africans," Mr Ollis said.
The public works minister has defended the expenditure on Mr Zuma's residence, arguing that the ministerial handbook on spending of public funds does not apply to the president.
Mr Zuma is gearing up for a difficult leadership battle at the governing African National Congress (ANC) conference in December.
Our reporter says his government has been plagued with reports of corruption and wasteful spending despite electoral promises to improve the lives of the poor.
The spending of taxpayers' money on the upgrade of roads near the rural home of South Africa's president should be investigated, the opposition says.