Twitter says the passwords of about 250,000 users have been stolen stolen in a sophisticated cyber attack similar to those that recently hit major Western news outlets.

Twitter's information security director Bob Lord says the security breach appeared to be similar to attacks suffered recently by other American media and technology companies including the New York Times and the Wall Street Journal.

"This attack was not the work of amateurs, and we do not believe it was an isolated incident," Mr Lord said in a blog post.

Mr Lord referred to an "uptick in large-scale security attacks aimed at US technology and media companies" as he told of Twitter detecting attempts this week to get unauthorised access to data in the company's network.

One of the users affected was the BBC's technology correspondent Rory Cellan Jones.

"I got a couple of emails from Twitter saying you need to change your password," he said.

"I then looked at a blog which said they've been detecting unusual access patterns, unauthorised attempts to access Twitter user data.

"They say the attackers might have had access to user names and encrypted passwords for about 250,000 users.

"They're advising those users in particular to change their passwords.

"They're telling everyone to be much more careful about how they set their passwords on Twitter."

The New York Times and the Wall Street Journal said the attacks on their systems pointed to attackers from China.

Twitter has not confirmed the source of the intrusion.

As a precaution, Twitter invalidated passwords of accounts at issue and sent people email messages telling them to create new passwords.

"The breach at Twitter is yet another wake up call - have we had enough yet?" said Mike Lloyd, chief technology officer at security firm RedSeal Networks.

"Attackers are clearly a step ahead of most defenders - it's a war between corporations and data thieves."

Sorry, this video has expired New York Times hacking 'tip of the iceberg' ( ABC News )

ABC/AFP