A Guardian investigation found that security experts were able to gather usernames, passwords and messages from phones using Wi-Fi in public places.
Professor Peter Sommer, a cyber-security expert at the London School of Economics, told the newspaper: "This is all very alarming. It means that literally millions of people who use Wi-Fi in public could be at risk."
He added: "If criminals are able to harvest the usernames and passwords of all the websites you visit, they could do significant damage in terms of identity theft and fraud."
The safest route for existing users of mobile phones, he explained, is to switch off their Wi-Fi when they leave home and only use it on systems they know to be secure.
Posted by Simon Jones
