With less than a month to go until the World Cup, the Brazilian government has sent in the tanks to restore order amid protests against the cost of hosting the international football competition.
Federal troops arrived in the World Cup host city of Recife on Thursday, where state police are on strike demanding better pay, to pacify the city following reports of looting and street violence.
"They are obviously using the proximity of the World Cup to pressure us to give into their demands," said government press officer Manoel Guimaraes for the state of Pernambuco, home to Recife, who did not specify the number of troops involved in the operation.
In Sao Paulo, which will host the opening game of the World Cup between Brazil and Croatia, protesters cut off access to the Avenida Paulista, coinciding with the morning rush hour, as police moved in to secure the main entrance to new stadium, Arena Corinthians.
"Our goal is symbolic. We don't want to destroy or damage the stadium," said Guilherme Boulos, head of the Homeless Workers Movement. "What we want are more rights for workers to have access to housing and to show the effects the Cup has brought to the poor."
In Sao Paulo alone, 27 people were arrested, 20 of them carrying Molotov cocktails, according to local media reports.
Meanwhile, in Rio de Janeiro, riot police used tear gas to break up protests as thousands took to the street demanding better housing and health care, adding to security concerns ahead of the World Cup. Rio will host the final match on 13 July.
In the capital Brasilia, protesters carried banners reading "FIFA Go Home". Demonstrations also hit Belo Horizonte, Porto Alegre, Fortaleza, Salvador and Campinas.
In pictures: Protests against the World Cup 2014 in Brazil
In pictures: Protests against the World Cup 2014 in Brazil
A member of the Homeless Workers Movement carries a Brazilian flag past burning tires during a protest against the money spent on the World Cup near Itaquerao stadium which will host the international soccer tournament's first match in Sao Paulo
Members of Brazil's Homeless Workers' Movement (MTST), who are living at the "People's World Cup Camp" which houses some 2,800 families of the movement in the district of Itaquera near Sao Paulo's World Cup stadium, Arena de Sao Paulo, block a road during a protest against the 2014 World Cup in Sao Paulo
Protesters in Sao Paulo, the country's biggest city, had blocked a major thoroughfare with burning tires and disrupted commutes elsewhere. The banner reads "Urban resistance"
Protesters burn tyres as they demonstrate against the FIFA World Cup Brazil 2014 outside the Arena Corinthians stadium in Sao Paulo
Demonstrators shout slogans during a protest against the 2014 World Cup in Sao Paulo
Black Bloc protesters Group clash with policemen during a protest against the World Cup in Sao Paulo
Hundreds of demonstrators protest against money spent on the World Cup preparations in Sao Paulo
Protests are taking place in various cities of the country and questioned the high spending on construction of stadiums and fight for better conditions and budget for health and education
People burn the national flag as they take part in the "International Day of World Cup Resistance" protest against the upcoming FIFA World Cup Brazil 2014 along the streets of Sao Paulo
Brazilians are angry at the billions spent to host the World Cup, much of it on 12 ornate football stadiums, one-third of which critics say will see little use after the big event
A man shouts slogan during the protest in Sao Paulo
Members of the Workers Without a Roof Movement (MTST) protest near the Arena Corinthians stadium against the upcoming FIFA World Cup Brazil 2014 in Sao Paulo. The Arena Corinthians will host the opening match of the FIFA World Cup Brazil 2014 between Brazil and Croatia
View of the illegal camp known as 'Copa del Pueblo' (People's Cup) set 4 kilometers from Arena Corinthians stadium two weeks ago by members of the group Movement of Workers Without Roof, who protest against the FIFA World Cup Brazil 2014 outside that stadium in Sao Paulo
People gather to protest against the upcoming FIFA World Cup Brazil 2014 in Rio de Janeiro. Brazil faced a test of its security preparations for the World Cup as demonstrators disgusted at the tournament's price tag called widespread protests. Ongoing strikes by police and teachers and the threat of a nationwide strike by federal police also raised fears of chaos with just few weeks to go until football's biggest global spectacle
A man carries a doll of Fuleco, the FIFA World Cup 2014 mascot during a rally to protest against the upcoming FIFA World Cup Brazil 2014 in Rio de Janeiro
An anti-government demonstrator dressed as comic book character Batman sits atop a monument of former slave Zumbi dos Palmares during a protest against 2014 World Cup in Rio de Janeiro
An anti-government demonstrator holds a banner atop a monument of former slave Zumbi dos Palmares during a protest against 2014 World Cup in Rio de Janeiro
Tear gas disperses demonstrators at a protest against the upcoming 2014 World Cup in Rio de Janeiro
Black Bloc protesters Group clash with policemen during a protest against the World Cup on the evening in Sao Paulo
Demonstrators hold a banner 'FIFA go home' as they protest against the World Cup FIFA soccer in Sao Paulo
The Brazilian government downplayed the prospect of renewed violence after Thursday's protests, insisting that there is "no reason to panic" ahead of the tournament.
"I’ve seen nothing that is related to the (World) Cup," said Brazilian Sports Minister Aldo Rebelo. "There’s no reason to panic ahead of receiving 3 million Brazilian tourists and 600,000 foreign tourists."
Many Brazilians are angry at the billions spent to host the World Cup. Protesters have said the government should focus spending instead on improving Brazil's health care, education, security and infrastructure systems.
Brazilian leaders had hoped the World Cup and then the 2016 Olympics in Rio would put a favourable spotlight on the country, showing advances over the past decade in improving its economy and pulling tens of millions out of poverty.
Additional reporting PA