A message on the group's Twitter account read: "TANGO DOWN - http://www.homeoffice.gov.uk For your draconian surveillance proposals! Told you to #ExpectUs!"
The message appears to refer to plans to expand the access the intelligence services has to people's emails, telephone calls and texts without a warrant, which are expected to be unveiled in next month's Queen's Speech.
The legislation is expected to instruct internet companies to install hardware enabling GCHQ - the Government's electronic "listening" agency - to examine the data "on demand".
The Government has defended the proposals as essential if police and security services are to stay one step ahead of serious criminals and terrorists.
Visitors attempting to access the Home Office site were told that it was temporarily unavailable.
Full story - http://news.sky.com/...rticle/16204656