An investigation is under way into how a computer ‘worm’ was able to strike the Twitter social network over the weekend, its co-founder Biz Stone said.

Mr Stone said that Twitter had suffered four separate attacks from a program known as a worm starting on Saturday and ending early on Monday.

It was set up to promote an alternative social networking site, StalkDaily.com, and was designed to automatically reproduce itself once clicked on.

It displayed Twitter messages, known as “Tweets,” on infected Twitter accounts, urging people to visit the website.

Nearly 10,000 unwanted Tweets had to be deleted to contain the potential damage. However, Mr Stone reassured Twitter users that no personal information was stolen during the incidents.

He wrote on his blog: “On a weekend normally reserved for bunnies, a worm took centre stage.

“We are still reviewing all the details, cleaning up, and we remain on alert.”

Michael Mooney, the 17-year-old founder of StalkDaily.com, admitted to creating the malicious worm. The high school student from Brooklyn, New York, said he wanted to promote his website as well as exposing Twitter’s weaknesses.

He said: “I really didn’t think it was going to get that much attention, but then I started to see all these stories about it and thought, ‘Oh my God’,”