Demonstrators gathered outside the city's Museum of Art on Avenida Paulista, waving union flags and carrying placards calling for labour reforms.

The 6x1 system requires six days of work for one day of rest. Proposed Constitutional Amendment PEC 221/2019 seeks to gradually reduce the working week from 44 to 40 hours and provide two days of paid rest without reducing wages.

The proposal was approved by the Chamber of Deputies on May 27 before being sent to the Senate.

Protesters argued that reducing working hours would give employees more time for their families, leisure and rest.

"First of all, quality of life. The worker needs to have quality of life, needs time to spend with their family, time for leisure, time to rest (...), the worker's mental issues, the worker's mental health; so it is essential that the worker puts an end to this 6x1 rota," demonstrator Marcelo said.

Another protester, Vivian, criticised Congress and the Senate and said demonstrations should continue until the 6x1 schedule is abolished.

"The Brazilian Congress and the Senate are aligned with the interests of the bourgeoisie, the rich, the bosses and not the working class. So demonstrations are important to win this right, which is to end 6x1," she stressed.

The proposal is advancing as Brazil's electoral calendar gathers pace. Senator and presidential candidate Flavio Bolsonaro strongly opposes the direct abolition of the 6x1 work schedule, describing the proposal backed by President Lula da Silva's government as a populist measure that could lead to mass unemployment.

Instead, Bolsonaro proposes a system where workers are paid according to hours worked rather than rigid weekly schedules.

Protester Danilo called for lawmakers to approve the proposal before the upcoming elections .

"Let us put an end to this rota that enslaves our Brazilian people . So today we are here on the streets pressuring Congress so that before the elections we can approve the end of 6x1 and establish a working timetable that allows our people to live and not just work," said the demonstrator.

Trade unions have also announced demonstrations outside the Senate in Brasilia on September 1, 2 and 3, as they push for progress on the proposal.