Brasilia: A cyber attack blocked traffic to the website of the Brazilian presidency and two other government sites on Wednesday, authorities said.
The self-styled Brazilian branch of the Lulz Security hacking collective claimed responsibility for the attacks.
Lulz members have claimed responsibility for recent attacks on the site of electronics giant Sony, along with the CIA web page and the US Senate computer system.
The Brazilian President`s office said in a statement that attacks on the website of the presidency, along with the nation`s internal revenue service and a government portal began around 12:30 am and lasted until 3 am.
The government said it stopped the hackers from obtaining data from the websites, but that the attacks made them inaccessible for about an hour.
Hours later, people who claimed to be Lulz members said on Twitter that they had taken down the website of oil company Petrobras, whose website was down Wednesday afternoon. Petrobras would not confirm whether the problems with its website were caused by an attack.
On a Twitter page in the name of the Brazilian branch of Lulz, posters justified the apparent attack on the Petrobras website by complaining about the price of gasoline in Brazil.
"Wake up Brazil! We no longer want to buy gas at 2.75 to 2.78 reals (USD 1.73 to USD 1.75) and export for half of that price!" stated one tweet from the group.