One in 10 websites in the UK are responsible for spamming their customers, new research has found.
The study, by Spam Ratings, claimed Britain had become one of the most "dangerous places to surf the internet in the world" due to doubling of spam over the last 12 months.
The rise of 110 per cent in spam meant the sites launched an average of five attacks per day and more than one million sites posed a risk to privacy and identity theft.
Andy Yates, co-founder of Spam Ratings, said: "Spam is a nasty and dangerous disease that has turned into an epidemic in the UK. Websites are the main cause and the main way the disease has spread."
"Too many websites sell data to third parties and are the source of the huge growth in unwanted and dangerous emails."
The research was also damning of some major UK companies, with one in five of their sites breaching email marketing best practice by sending out emails to customers without asking them to opt in to the service.
Brands responsible included Ticketmaster, Argos, Money Supermarket and Woolworths.
"Consumers need to think twice about the origin of spam and be cautious and alert when shopping online or signing up to websites," added Yates.
Graham Miller, director of www.shopsafe.co.uk, warned retailers they needed to take the issue more seriously.
"The online retail world needs to wake up to the fact that consumers are still nervous about shopping online," he said.
"Our own research earlier this year shows this is an issue for 90 per cent of shoppers. Concerns over spam and the threat of attack play a large part in this and the people who run these sites need to act to protect shoppers and save their own reputations."
