Brazilian union leaders said on Monday that General Motors is planning to lay off 350 workers at its Sao Caetano do Sul plant near the industrial city of Sao Paulo, Dow Jones said.

According to the report, the Metalworkers Union at the Sao Caetano plant said workers held a one-hour work slowdown early on Monday to protest the expected job losses.

Dow Jones noted that the news comes as Brazil's automotive sector is suffering through one of the worst sales slumps seen in a decade. New vehicle sales plunged 8.5% over the first five months of this year.

The news agency also noted that big vehicle manufacturers in Brazil, like Ford and Fiat, have already sent workers out on group holidays in June and July, in an effort to avoid layoffs and at the same time keep inventories from piling up at their plants.

Volkswagen, one of Brazil's big three along with GM and Fiat, has had a four-day work week in place since the end of last year, Dow Jones added.