Twitter: Account hack affects 250,000users

By Rory Cellan-Jones Technology correspondent

Mr Lord said in a blog post Twitter had discovered unauthorised attempts to accessdata held by the website, including one attack that was identified and stopped momentsafter it was detected.

"This attack was not the work ofamateurs, and we do not believeit was an isolated incident,"

he wrote. Mr Lord did not mention who the hacker was:

"The attackers were extremely sophisticated, and we believe other companies and organisations have also been recently similarly attacked." "For that reason we felt that it was important to publicise this attack while we still gather information, and we are helping government and federal law enforcement in their effort to find and prosecute these attackers to make the internet safer for all users."

Internet security specialist Graham Cluley warned Twitter's announcement that emails would be sent to users may prompt a spate of spam emails"phishing" for sensitive information. He says people should be cautious about opening emails which appear to be from Twitter.