Hacker collective Anonymous has attacked and brought down the websites of the US Department of Justice and New Zealand police in retaliation for the shutdown of media-sharing site Megaupload.

Anonymous responded to a Justice Department indictment ordering Megaupload's shutdown and arrest of the founders with a statement on Pastebin "OpMegaupload" against US authorities and media music industry sites, alleging censorship. The indictment accused the founders of racketeering conspiracy, money laundering and plotting to commit copyright infringement.

"Popular file-sharing website megaupload.com gets shutdown by U.S Justice - FBI and charged its founder with violating piracy laws. Four Megaupload members were also arrested," read Anonymous' statement.

"We Anonymous are launching our largest attack ever on government and music industry sites. Lulz. The FBI didn't think they would get away with this did they? They should have expected us."

Anonymous warned that it would target justice.gov, universalmusic.com, riaa.org, mpaa.org, copyright.gov, hadopi.fr, wmg.com, usdoj.gov, bmi.com and fbi.gov

They attacked the US Department of Justice (http://usdoj.gov) and the New Zealand police (http://www.police.govt.nz) with Distributed Denial of Services (DDos) attacks.

The attacks followed the arrests in New Zealand of Megaupload founders Kim Dotcom and Kim Tim Jim Vestor, 37. The FBI thanked New Zealand authorities for "collaborating" in the arrests.

"US Department of Justice http://usdoj.gov TANGO DOWN. Cause ur doing s***s bitches," tweeted the Anonymous account "Anonymous IRC".

Another tweet read: "New Zealand police http://www.police.govt.nz tango down. Cause u suck bitches."

The attack is the latest development in a long line of clashes between Anonymous and US law enforcement. Earlier in January Anonymous mounted a separate cyber-attack on the FBI's network, releasing an internal document allegedly taken during the hack. The hack was later revealed as a revenge attack protesting against US law enforcement's treatment of Occupy protesters.

The collective later reported leaving the notorious "butthurt" form previously seen in July during an earlier assault on the FBI. "The CC'd zine we sent to them also includes a Butthurt form in case they need it... #Anonymous #AntiSec #LulzXmas #FillTheFormB[**]ch," boasted AnonymousIRC.

The collective had also directly targeted the FBI for its involvement in the arrest of several alleged Anons in 2011. For a full look at Anonymous activity in 2011, read the International Business Times UK's sum-up piece, 2011 The Year of the Hacktivist: When Anonymous Finally Grew Up.