RIO DE JANEIRO — Federal police on Wednesday threatened to stage a nationwide strike during the monthlong World Cup if Brazil’s government doesn’t increase their pay and improve working conditions.

Officers held a protest rally outside the Rio de Janeiro concert hall where national team coach Luiz Felipe Scolari was announcing his roster for the soccer tournament, which begins June 12.

About 50 protesters covered their mouths with red scarves and held banners. They stood next to a life-size inflatable white elephant to complain about the high costs that the World Cup has brought to a country still struggling with deficient public services.

“We gave all possible deadlines,” said Andre Vaz de Mello, president of the federal police union. “If we don’t see a government response to change things, we will stop working during the World Cup.”

At Rio’s famed Copacabana Beach, other protesters lined up soccer balls with red and black crosses on the sand, showing photos of victims who have been killed or injured in gunfights in the city’s supposedly “pacified” slums.