Two UK members of hacking collective LulzSec have pleaded guilty to a string of cyber attacks on a number of high profile websites.

Ryan Cleary, 19, and Jake Davis, 18, admitted being part of LulzSec. Davis was also known as Topiary and was regarded as the hacking group’s primary spokesperson. He was based in the Shetland Islands while Cleary was from Wickford in Essex.

The pair plotted to attack a huge number of websites including, the UK Serious Organised Crime Agency (SOCA), the NHS, News International, Sony, HBGary and HBGary Federal and 20th Century Fox. The duo was accused of hacking as well as launching DDoS attacks, where websites are flooded with so much traffic they crash.

Cleary also pleaded guilty to further charges, including hacking into US military computers based within the Pentagon.

Cleary and Davis pleaded not guilty to the charge of posting "unlawfully obtained confidential computer data" to sites such as The Pirate Bay and PasteBin.

During today’s hearing at Southwark Crown Court alleged co-hackers Ryan Ackroyd and a 17-year-old who cannot be named for legal reasons, denied all similar charges.

All four will face trial in April next year. With the exception of Cleary, all the suspects were released on bail.

Cleary was recently indicted by a federal grand jury in Los Angeles on similar hacking charges.

LulzSec first emerged in 2011, claiming to be an offshoot of infamous hacking collective Anonymous. It attacked a string of high profile websites before the group imploded in March this year when it was revealed that the hacker known as Sabu, LulzSec’s leader, was in fact an FBI informant.

According to Fox News, he was turned after being arrested in June 2011 and provided details of Anonymous and LulzSec members in return for avoiding jail.