Federal Police have issued a stern warning to computer hackers who have been trying to crash Australian government websites. Hacking movement Anonymous has been credited with infiltrating government and company websites across the world, and now members of the group have set their sights on Australia. Acting under the banner of the Anonymous movement, hackers yesterday unsuccessfully tried to bring down the Australian Security Intelligence Organisation and the Defence Signals Directorate websites. Both agencies say their websites have not been infiltrated and they do not store classified information there. Federal Police are warning hacking-related offences can carry a jail term of up to 10 years. "The difficulty is finding this loosely-based group who advertise their activism online but have been notoriously difficult to pin down in person," a spokesperson said. Anonymous says the hacking aims to protest against the Federal Government's plans for surveillance powers it claims would allow more personal details to be stored on web servers. The group is already facing a police investigation into allegations its members have taken 40 gigabytes of confidential customer data from AAPT, one of Australia's biggest phone companies.