JOHANNESBURG - Protesters, angered by a change in municipal boundaries which they fear will leave them worse off for social services, torched 13 schools in South Africa's northern Limpopo province, police said as tensions rose ahead of local polls in August.

The latest protests were triggered by a high court ruling upholding a decision to shift some districts from one municipality's jurisdiction to another.

Many protesters said the change meant the quality of social services would change, leaving them worse off.

With elections scheduled for August 3, the demonstrations over services are starting to take on an increasingly political tone, suggesting they could get worse in the next few months.

Police said residents in Vuwani district and nearby areas set alight a post office and other government buildings on Monday and Tuesday nights leaving smouldering structures behind.

Residents had also set up roadblocks to the area, Limpopo police spokesperson Colonel Malesela Ledwaba said.

The protests began after the High Court upheld the Demarcation Board's decision to include the districts, currently under Makhado municipality, into the Malamulele district after residents had filed a case to oppose the change.

"What we are requesting from the police is that they ... provide more manpower in the area and ensure that important public infrastructure is protected," said Limpopo Premiere Stanley Mathabatha speaking on local TV news channel, eNCA.

The Basic Education Minister Angie Motshekga said the actions of protesters undermined government efforts to improve education and infrastructure.

"It is not only a waste of taxpayers' money to lose valuable existing infrastructure but disrespects the hard work of every law abiding member of society," Motshekga said in a statement.

Opposition political parties are seizing on the anger as evidence of the failings of the ruling African National Congress (ANC), in providing services around the country.

The ANC has said it is still best placed to lead the country having successfully campaigned against white minority rule under apartheid which ended in 1994.