Brazil's federal police started on Tuesday a two-day work stoppage to demand better wages and improved security for the World Cup.
As an anticipation of what was to happen on Tuesday, around 100 police officers protested on Monday along Sao Paulo's Avenida Paulista thoroughfare outside a building hosting a local authority seminar on World Cup security.
We have reached a critical situation, Jones Borges Leal, chairman of Brazil's national federation of federal police, said at a protest march in business hub Sao Paulo. Federal police claim their salaries have been frozen for seven years.
We have a series of activities programmed for the year and hope not to have to bring them to a halt during the World Cup, which starts June 12, he added. We hope it doesn't come to that.
Sao Paulo is scheduled to host the opening match between Brazil and Croatia.
The protesting officers brandished slogans demanding FIFA standard federal police -- alluding to the tough security standards world football's governing body is demanding for the tournament.
Police say just 30% of officers will provide a minimum service during their colleagues' two day strike in a country beset by protests in recent months against corruption and the cost of hosting the Cup.
Brazil's security system needs reforming, said Borges. We don't have sufficient resources to guarantee the security of Brazilians, still less of foreign visitors, he complained.
Brazil expects to welcome around 600,000 foreign visitors for the month-long soccer event.
According to Borges, despite being a continent-sized country Brazil only has 10,000 federal police nationwide to oversee border and airport security, the safety of public buildings and also issue passports.
They are also responsible for security of the head of state, President Dilma Rousseff, and her government's ministers. However each of Brazil's 27 federal states have federal, military and civil police.
A decade ago, former president Lula da Silva indicated he would create a unitary public security structure via a constitutional amendment but the plan has fallen into abeyance.
The Brazilian government has said it has a specially trained force, 10.000-strong to help manage security the coming World Cup. President Dilma Rousseff has warned that if protests and acts of violence against private or/and government property continue, she will call in the Armed Forces to ensure everything runs smoothly.