James Jeffery, a member of the Anonymous hacking collective, has pleaded guilty to being behind a cyber attack on the British Pregnancy Advisory Service.
The 27-year-old, of Wednesbury, West Midlands, admitted two offences under the Computer Misuse Act during an appearance at Westminster Magistrates' Court today.
Prosecutors told the court Jeffery targeted the BPAS website after two women he knew had terminations.
He stole 10,000 patient records and threatened to release them online, and also published the Anonymous logo and an anti-abortion message on the site.
Jeffery then used his 'Pablo Escobar' Twitter account to boast about his exploits and provided proof of them to fellow hackers by printing the name and log-in details of a BPAS administrator.
The court was also told he had identified vulnerabilities in the websites of a number of major international organisations and that the Metropolitan Police are now investigating alleged cyber attacks on the CIA, FBI, US Navy and Houses of Parliament.
Jeffery was remanded in custody and will be sentenced at Southwark Crown Court at a later date.