“It is only a matter of time” before firms such as Tesco and Sainsbury’s are attacked by cyber criminals, according to a specialist panel at this week’s InfoSecurity Europe event.

The “white hat” hackers, security experts specialised in detecting flaws in corporate IT security infrastructure, warned that tactics along the lines of the attacks that crippled sites for Estonia's banks and schools could be used to paralyse operations of retailers with an online presence.

"We had all been waiting for this kind of attack to happen,” said founder of online crime monitoring site Zone-H Roberto Preatoni.

"It was just unfortunate that Estonia was the first country to experience it [hacker attacks]. But very soon, [western] companies and countries will be getting attacked for political and religious reasons,” said Preatoni.

The rise in online crime in China came in handy for western countries to disguise their own spying activities, Preatoni told the BBC.

"It's too easy to blame China. In fact, legitimate countries are bouncing their attacks through China. It's very easy to do, so why not?

"My evil opinion is that some western governments are already doing this."