Two members of the notorious hacking group Lulzsec have today pleaded guilty to a string of cyber-attacks on major organisations.

Ryan Cleary, 19, and Jake Davis, 18, admitted to charges of hacking websites across Britain and the US. The targets included the NHS, News International, Sony, Nintendo, Arizona State Police, and film studio 20th Century Fox.

Cleary and Davis plotted the attacks alongside unknown members of other Internet hacking groups Anonymous and Internet Feds, as well as fellow Lulzsec associates. The crimes in question relate to a host of distributed denial of service (DDoS) attacks, where websites are flooded with traffic to make them crash.

Appearing in the dock at Southwark crown court with Davis earlier today, Cleary confessed to four further charges, including hacking into US Air Force Agency computers based at the Pentagon.

But alleged co-hackers Ryan Ackroyd, 25, and a 17-year-old boy from South London, deny their involvement in the DDoS attacks and will stand trial on 8 April next year.

Cleary, who suffers from Asperger's syndrome, was arrested last June. His lawyers recently vowed to "fiercely contest" any applications that may be made for his extradition to the US.