A row has broken out between Wikileaks and one of the newspapers it collaborated with to leak US diplomatic cables. The whistle-blowing group said unredacted versions of the 251,000 diplomatic cables had been leaked on the internet. Wikileaks blamed the disclosure on the Guardian newspaper and said it had started legal action against the paper. The newspaper has strongly denied the claims, blaming a "security breach". In a short statement on Twitter, Wikileaks said: "A Guardian journalist has, in a previously undetected act of gross negligence or malice... disclosed top secret decryption passwords to the entire, unredacted, Wikileaks Cablegate archive.

Millions of web users are being asked to reset their passwords as concerns spread over a major hacking attack.

A teenager has been jailed for 16 weeks after he refused to give police the password to his computer.

Questions used as security checks on websites need to be replaced by more complex tests to establish a person's identity, say researchers. A study has shown how easy it is to guess the answer to common questions, such as someone's mother's maiden name. It found attackers will be able to break into 1 in 80 accounts if they get three chances to guess answers.