A 26-year-old has admitted hacking the websites of major institutions including the National Health Service, Sony and News International.

Ryan Ackroyd, from Mexborough, South Yorkshire, was due to stand trial charged with taking part in a string of cyber attacks, but yesterday pleaded guilty to one charge of carrying out an unauthorised act to impair the operation of a computer, contrary to the Criminal Law Act 1977.

Southwark Crown Court heard he admitted being a member of hacking group LulzSec, acting as a hacker to access websites for Sony, 20th Century Fox, the NHS, Nintendo, the Arizona State Police and News International between February and September 2011.

Prosecutor Sandip Patel told the court: "He was the hacker, so to speak. They turned to him for his expertise as a hacker." He said Ackroyd admitted using the persona of a 16-year-old girl, called Kayla, on the site. He will be sentenced on May 14.

Earlier, the court heard that fellow hackers Mustafa Al-Bassam, 18, from Peckham, south London, and Jake Davis, 20, from Lerwick, Shetland, had also pleaded guilty to hacking and launching cyber attacks.