A COMPUTER expert from York has admitted hacking into the Facebook website, in one of the biggest such crimes ever to come before a British court.

Glenn Mangham, 26, from Cornlands Road in Acomb, pleaded guilty at Southwark Crown Court yesterday to hacking into the social networking site between April and May this year.

The court heard Mangham’s actions sparked a major security alert in the United States, where the authorities feared it was industrial espionage.

Mangham, a software development student, had previously shown web giant Yahoo! how it could improve security and wanted to do the same for Facebook, the court heard.

Sandip Patel, prosecuting, said his actions caused no economic loss but concerned American authorities including the FBI.

Mr Patel said Mangham's actions were the "most effective and egregious example of hacking into social media that has come before a British court".

Mangham downloaded his own computer programmes on to Facebook's servers and saved "highly sensitive intellectual property" on to an external drive so he could work on it off-line, a move which Mr Patel said required “considerable expertise".

Facebook discovered the infiltration during a check, but the defendant deleted his electronic footprint to cover his tracks, the barrister said.

For the defence, Tom Ventham said Mangham was highly intelligent and of good character.

He said Mangham was an ethical hacker who had a "high moral stance" and said Yahoo! had "rewarded" him for pointing out its vulnerabilities previously.

"That was his plan here but the activity was found by accident," said Mr Ventham.

He added that when he was arrested he made a "copious" admission and gave the investigating officer a "Cambridge tutorial into computer science".

A Facebook spokesman said in a statement issued after the hearing: "At Facebook nothing is more important to us than the security and integrity of our site, and we take any attempt to compromise our security network incredibly seriously.

"We work closely with law enforcement agencies and the police to ensure that offenders are brought to justice.

"This attack did not involve an attempt to compromise or access user data."

Mangham will be sentenced in February.