Hacker attacks forced Brazil to shut down its presidential website and other government sites temporarily on Thursday, one day after cyber attacks briefly disabled other government sites.

The Lulz Security group of hackers took credit for some of the attacks and said it had released what it said was personal data on President Dilma Rousseff and the mayor of Sao Paulo.

It was the latest in a global wave of cyber attacks on companies, organizations and governments.

The attack on the presidency website "generated a lot of traffic, designed to make the site unavailable. It wasn't to steal information," a government spokeswoman told Reuters.

The website posts presidential speeches, laws and other public information, another spokesperson said. The site was back on the air later in the day.

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Several other government websites were taken off-line to bolster security following similar attacks, including the sports ministry site, which was still down in the early evening. A ministry spokeswoman said the attack did not affect data or compromise "the heart of the system."

But the LulzSec group of hackers in Brazil claimed on Twitter to have copied protected data from the ministry site, showing what the group said was data on federal money sent to states that will host the 2014 soccer World Cup.

The group also released what it said was personal data on Rousseff and Sao Paulo Mayor Gilberto Kassab, including phone numbers for both. On Thursday afternoon the telephone numbers listed either did not work or were not attended.

Other government sites have been attacked recently. The sites for Brazil's federal government, the presidency and the tax collection agency were inaccessible to the public for about two and a half hours earlier in the week.

LulzSec has made widely publicized assaults on Sony Corp, the CIA, News Corp's Fox TV and other targets. The attacks have mostly resulted in temporary disruptions to websites and the release of user credentials.

LulzSec said on Monday in a Twitter message that it was seeking to hack government websites to leak "classified government information.