A British computer hacker affiliated to the group Lulz Security pleaded guilty Tuesday to cyberattacks on institutions including Sony, Britain's National Health Service and Rupert Murdoch's News International.

Ryan Ackroyd admitted one count of carrying out an unauthorized act to impair the operation of a computer.

Prosecutors say the 26-year-old accessed websites belonging to Sony, 20th Century Fox, the NHS, Nintendo, the Arizona State Police and News International between February and September 2011.

He will be sentenced May 14 at Southwark Crown Court in London. Other charges against him are being dropped.

Three other British hackers — 18-year-old Mustafa Al-Bassam, 20-year-old Jake Davis and Ryan Cleary, 21 — had previously pleaded guilty to launching distributed denial of service attacks on organizations including the CIA and Britain's Serious Organized Crime Agency. Denial of service attacks work by overwhelming sites with traffic