Hacker group Anonymous has breached Brazil's federal district websites following its brazen attack on the US online security site.

In a retaliation hack against the US government's decision to close Megaupload.com, the collective targeted hundreds of Brazilian sites that share the url, df.gov.bf.

More than 30 government websites have been taken down, including the Brazilian senate and the central government's sites. Anons @Havittaja and @theevilc0de are believed to be the main culprits responsible for the attack.

Internet news site G1, owned by television network Globo, confirmed the attacks but said the federal district's information technology team was able to fix them.

Hackers also shut down the website of popular Brazilian singer Paula Fernandes. They posted the image of a grim-faced joker with a message saying, "If Megaupload is down, you are down too." It was signed "GhostofThreads."

The FBI closed down Megaupload, one of the world's largest file-sharing websites, on 19 January. The bureau said Megaupload was running an international crime ring that cheated copyright holders out of US$500m (£320m) in revenue.

In retaliation, Anonymous launched a distributed denial of service against the FBI - the largest attack to date.

The FBI DDoS attack was part of a wider campaign designed to protest against the US government-ordered shutdown of Megaupload.com. Following an initial statement, the collective issued a fresh claim via its AnonymousIRC Twitter feed claiming the DDoS was its largest ever.

"Yesterday was epic. The Largest Attack Ever by #Anonymous - 5,600 People Confirmed. #Megaupload +INFO >> goo.gl/i1rUw," read the tweet.

Since the FBI DDoS the collective has mounted further assaults on justice.gov, universalmusic.com, riaa.org, mpaa.org, copyright.gov, hadopi.fr, wmg.com, usdoj.gov and bmi.com. Most recently the collective claimed responsibility for attacks on the USDepartment of Justice and MGM.