Half of all spam involves lottery scams making them one of the fastest growing areas of cyber-crime, according to research commissioned by Microsoft across Germany, Italy, Denmark, the UK and The Netherlands.

The problem is worse in the UK where around 62 per cent of spam emails are lottery scams.

Disturbingly, 16 per cent of those who received 'lottery spam' opened at least some of them, and 10 per cent have replied to one of these emails and 20 per cent admitted to clicking on links inside the emails.

Three per cent of respondents said they have lost money to scammers over the past 12 months.

"Internet lottery scams are one of the fastest growing areas of cyber-crime, " said Ed Gibson, chief security advisor for Microsoft in the UK.

"The scams are of increasing concern to international law enforcement, offering criminals a low-risk opportunity to steal money from internet users."

Microsoft said that the scams are particularly insidious in that they work purely through social engineering, rather than by exploiting a technical flaw in software.

As a result, they represent huge challenges to law enforcement, as they are extremely difficult to track, and even more difficult to catch and prosecute fraudsters.

"Lottery scams entice people with the false promise of large sums of money for little or no effort on their part," said Jacques Erasmus, a security specialist from Prevx and former 'white hat' hacker.

"Once a person is involved in the scam, they are asked to pay certain amounts of money to expedite the process such as an up front 'administration fee'. They end up not making a single pound."

A study by the Internet Crime Complaint Center revealed that advance fee frauds such as lottery scams are the costliest type of internet fraud with a median of $5,000 per victim.

"We want to raise awareness of a growing type of internet crime. Make no mistake, the criminals that perpetrate these crimes are extremely clever and devious, and unfortunately successful," added Gibson.