Sensitive information should not be sent over public wi-fi hotspots, to avoid hackers stealing it, Europe's top cybercrime police officer has warned, according to BBC News.

Troels Oerting, head of Europol's cybercrime centre, said people should send personal data only across networks they trusted. He said the warning was motivated by the growing number of attacks being carried out via public wi-fi.

Europol is helping a number of countries after such attacks, he said.

"We have seen an increase in the misuse of wi-fi, in order to steal information, identity or passwords and money from the users who use public or insecure wi-fi connections," he said.

"We should teach users that they should not address sensitive information while being on an open insecure wi-fi internet.

"They should do this from home where they know actually the wi-fi and its security, but not if you are in a coffee shop somewhere you shouldn't access your bank or do all of these things that actually transfer very sensitive information."

Oerting said Europol, which helps co-ordinate investigations into organised crime across Europe, was assisting several member states who had seen attacks carried out on wi-fi networks.

The attackers were not using novel techniques, he said, but relied on well-known approaches that attempt to trick people into connecting to a hotspot that, superficially, resembles those seen in cafes, pubs and restaurants and other public spaces.

Large companies were also falling victim to this type of crime, said Charlie McMurdie, former head of the UK's cybercrime unit and now a senior security analyst at PWC, because they were not watching out for the rogue hotspots that are regularly turning up.

Sometimes, said Ms McMurdie, attackers used hotspots to get at particular individuals rather than to grab all the data flowing from everyone using a public network.

Everyone needed to be aware of what they were putting at risk when they use wi-fi networks and the data it can potentially hand over to criminals.

"There is the need for raising awareness of what the vulnerabilities are and what you should be doing to protect yourself whether you're on the move or in a physical location," she said.