An alleged computer hacker has appeared in court accused of conspiring with three British teenagers to bring down the websites of the CIA and Serious Organised Crime Agency.

Ryan Ackroyd, 25, appeared at Westminster Magistrates court in London on Friday charged with computer hacking offences for the so-called "hacktivist" group, LulzSec.

Ackroyd is accused of attacks on the NHS and News International, publisher of the Sun, as well as police authorities in the UK and US.

The Doncaster man is the last of four British males to appear in court in the UK in connection with attacks by LulzSec, a spin-off group linked to the hacking collective Anonymous.

He faces two counts of conspiring with Jake Davis, 18, Ryan Cleary, 19, and a 17-year-old boy, who cannot be named for legal reasons, to do "an unauthorised act with intent to impair or with recklessness as to impair the operation of a computer" between 1 February and 30 September 2011.

Wearing blue jeans, a brown Bench zip-up top and white trainers, Ackroyd spoke only to confirm his name and address.

District judge Howard Riddle granted him bail until a plea and case management hearing at Southwark crown court on 11 May, on condition that he does not access or have in his possession any device that could access the internet.

Ackroyd, of Oak Road in Mexborough, Doncaster, was charged on 6 March along with the unnamed 17-year-old from south London, who appeared at West London youth court on Wednesday accused of two counts of conspiracy to do an unauthorised act with intent to impair or with recklessness impairing of an operation of a computer or computers.

He will appear at Southwark crown court alongside Cleary and Davis on 11 May.