Demonstrators stoned and burned buses in black townships at the start of important municipal elections Wednesday, but authorities reported generally peaceful polling nationwide under unprecedented security measures.

State-run radio reported a low voter turnout but said it was expected to pick up later in the day.The elections are deemed crucial to President Pieter W. Botha's white minority government, testing the growth of the right-wing white electorate, which opposes Botha's policies of limited racial reform.

Botha's government also is hoping for a high voter turnout in black areas as an endorsement of its policies.

For the first time, blacks in urban townships, minority whites and people of mixed race are voting on the same day for segregated city, town and township councils.

Police said at least nine Molotov cocktail attacks occurred in black townships on the eve of the election and said one man had been killed in Durban and two other people injured in sporadic incidents of unrest elsewhere.

The Public Transport Co. said bus traffic through black townships in the Johannesburg-Pretoria area was generally normal Wednesday, with the exception of the Emdeni district of the sprawling black satellite city of Soweto and the eastern township of Thokoza.

In Emdeni, mobs of blacks stoned three buses Wednesday morning, smashing windshields and setting one ablaze after dragging its driver outside and beating him, a transport spokesman said. The driver was not seriously injured, he said.

In Thokoza, police sealed the only entrance to the township and authorities had no immediate comment on the situation there.

In Durban, official sources reported several buses were stoned in the black townships of KwaMashu, Umlazi and Claremont to discourage people from voting and supporting a call for a one-day protest.

Overnight, witnesses said dissidents in Indian townships erected signs in fluorescent paint calling for a boycott of the elections.

But Brig. Leon Mellet, spokesman for Law and Order Minister Adriaan Volk, said the unrest was relatively minor.

Unprecedented security measures were in force to protect blacks who wanted to vote despite calls for a boycott and warnings the outlawed African National Congress intends to disrupt polling, officials said.

"We've got foot patrols all over the place," Mellet said. "The police presence at the polling booths is very high."

Anti-government church leaders, among them Archbishop Desmond Tutu, appealed for calm amid security clamps on dissent and opposition calls for protests.

"The South African police will not tolerate any form of intimidation or violence," National Police Commissioner Hennie de Witt said Tuesday.

Analysts deem the elections crucial to Botha's minority white government in the face of vote-catching campaigns for a return to harsher apartheid policies by the right-wing white Conservative Party.