A “worm” spreading spam messages promoting another website was first introduced into Twitter in the early hours of Saturday.

Within hours it had spread across the network, infecting scores of accounts and forcing administrators to delete 10,000 messages to stop it infiltrating further.

Users spread the virus simply by clicking onto an infected page.

They then began unwittingly sending out messages – or “tweets” – to other users promoting the site StalkDaily.com.

Despite efforts to curb the virus, Twitter was hit by a second, more intense, bout of attacks later in the day and another early on Sunday.

Twitter then announced early on Monday that it was facing a new “manifestation” of the worm. Messages advised users not to click on links until the problem was rectified.

The website emphasised that no sensitive information such as passwords or telephone numbers had been compromised and suggested it would take legal action against the perpetrators.

A worm is a computer programme which spreads through a network by making copies of itself when users inadvertently click on something.

According to the Twitter news service BNO, a teenager from New York claimed responsibility for the worm “Mikeyy” saying that he had been bored.

He said that he had been trying to highlight ways in which the phenomenally popular site could be vulnerable to hackers.

“I did this out of boredom to be honest,” he was quoted as saying.

“I usually like to find vulnerabilities within websites and try not to cause too much damage.”

Twitter – a so-called “micro-blogging” service – has seen phenomenal growth in the last year rivalling Facebook and MySpace as one of the most popular social networking sites among British users.

It played a key role in the US election with candidates including Barack Obama posting messages on the site and British celebrities such as Stephen Fry have also become high profile users.

Users post short tweets either directly onto the site or by mobile phone.

These are then forwarded on to their network of friends and contacts.