RIO DE JANEIRO (AP) — Violent protests have provided an early security test before Brazil's warm-up event for the 2014 World Cup, although FIFA expressed "full confidence" on Friday that the authorities have shown they can manage disorder in the streets.

There were clashes with police on Thursday night in Sao Paulo and Rio de Janeiro after thousands protested against rising bus and subway fares.

And in Brasilia, at the venue staging the opening match of the Confederations Cup on Saturday, about 200 people burned tires and blocked the main road in a protest against the cost of staging the showpiece FIFA events.

Crime had been flagged up as the main security concern for the football tournaments in a country with a high murder rate and where armed robberies are common place, but civil disobedience has emerged as the early safety issue.

FIFA sought to downplay the threat such confrontations could pose to fan safety at the eight-nation Confederations Cup, which is a key test of Brazil's readiness to stage the 32-team World Cup in a year.

"We respect fully the right of everybody to protest," FIFA spokesman Pekka Odriozola said. "We are monitoring the situation. We are in touch with the local authorities.

"We fully trust the local authorities and we have full confidence in what they are doing ... they are ready for any circumstance."

Later Friday, the Brazilian government, police and military combined to brief journalists on the full array of weapons and machinery at their disposal, backed by a security force of 54,000.

Drones will be used to monitor cities from the skies, although Colonel Wanius Amorim of the State Civil Defense insisted that these would not be "weaponized."

Officials maintained that the response to protests would be proportionate, denying excessive force was used during the confrontations on Thursday.

In the streets of Sao Paulo's central area, protesters clashed with police who fired tear gas trying to disperse the crowd. Police said 40 people had been detained, some with knives and gasoline bombs.

The clashes were less troublesome in Rio de Janeiro where about 2,000 people protested against rising transport costs.

"We only act if there is any unlawful act that affects the population as a whole," Lieutenant-Colonel Marcelo Rocha of Rio de Janeiro's military police force said through a translator.

The government said only it would solve any problems "very quickly" while pointing to the right of people to protest.

"Demonstrations will occur and that's healthy ... and the right to protest has to be guaranteed," said Jose Monteiro, an operations director at the Ministry of Justice.

"The role of the security forces is to ensure people can express themselves," he added.

The Confederations Cup opens on Saturday with host Brazil playing Japan in Brasilia, where a cloud of black smoke rose near the match stadium on Friday after the tire-burning protest.

Protester Edson da Silva said they were against "all the money that was spent by the government" to prepare the country for the World Cup.

___

AP Sports Writer Tales Azzoni in Brasilia contributed to this report.