In what seemed to be the latest technological feat, scientists have developed a laptop which can shout 'stop, thief!' when stolen.

In fact, a team at a leading software company, Front Door Software Corporation, has designed a software programme, called Retriever, that can make the laptop speak out when it has been reported missing.

The software, which costs pound 21, actually allows users to display alerts on the missing computer's screen and even to set a spoken message such as a shout or a warning.

Although tracking software for stolen laptops has been on the market for some time, this is understood to be the first that allows owners to activate recorded messages, 'The Times' reported.

Carrie Hafeman, company's chief executive, said that if owners tick a box indicating that their computer has gone, when it is started up, "a big red and yellow banner pops up, saying 'This laptop is lost or stolen'."

The message can be set to reappear every 30 seconds, no matter how many times the thief closes it. "One customer sent a message saying, 'You are being tracked. I am right at your door'," she was quoted as saying.

In the latest version, people can even add a spoken message. The default through the computer's speakers is: "Help this laptop is reported lost or stolen. If you are not my owner, please report me now."

The "talk" update of Retriever programme works with Microsoft Windows XP and Vista and a version for Mac users is in the pipeline, Hafeman said.