Megaupload, one of the internet's largest file-sharing sites, has been shut down by officials in the US.

The site's founders have been charged with violating piracy laws.

Federal prosecutors have accused it of costing copyright holders more than $500m (£320m) in lost revenue. The firm says it was diligent in responding to complaints about pirated material.

In response, the hackers group Anonymous has targeted the FBI and US Department of Justice websites.

The news came a day after anti-piracy law protests, but investigators said they were ordered two weeks ago.