Inadequate Wi-Fi security is leaving many firms exposed, according to two new reports by antivirus specialist Kaspersky Lab and RSA Security.

Kaspersky Lab's research, conducted at the end of last month, found that 49 percent of Wi-Fi networks in the capital are vulnerable to attack because they do not use data encryption. Canary Wharf was the most secure area but the figure for unencrypted networks there was still 40 percent.

"It's symptomatic of every emerging technology – security tends to [come after] functionality," said David Emm of Kaspersky Lab. "On the one hand protection of devices has got better over the years, but [IT managers] should be thinking in terms of encryption, so what's transmitted is secure."

Emm also advised firms to create unique passwords to ensure that corporate laptops connecting to the internet do not have their default Wi-Fi settings in place.

RSA's findings were slightly less grim for firms. It found a lower figure - around a quarter of business networks - were open to attack. RSA said the number of wireless hotspots in the capital rose by over 70 percent in the last year, and many companies face the danger of data theft and malware via their mobile devices.