Telewest has announced that it will attempt to introduce a full set of security software services for customers this summer, after being blacklisted by the Spam Prevention Early Warning System.

The cable company was criticised after the anti-spam organisation, which advises firms around the world on which IP addresses to filter out, reported that its customers suffered very high levels of virus infections.

"We are aware of the increase in email volumes due to customers' PCs which have been infected by worms and viruses," said a Telewest spokesman.

"This is due to the recent spate of worm outbreaks, such as the Sober variant that hit the internet last week. We are currently contacting affected customers to help them clean their PCs."

The spokesman added that the company is planning to introduce a suite of security utilities, including antivirus, anti-spam and pop-up blocking software.

No details are available on availability or pricing, but Telewest expects to offer a graduated service for different types of subscription.

NTL announced last week that it is to offer a free antivirus service to its customers.

The debate over whether ISPs should provide such services was one of the hot topics at last month's InfoSec show, when security experts lined up to criticise ISPs for failing to protect their customers.

"What customers should look at is the duty of care from ISPs," said Andy Buss, senior analyst at Canalys.

"A lot of users do not want ISPs mucking in their business, but customers connecting to an ISP network should expect a certain level of protection from other customers of the ISP."