More than a quarter of Britons using the internet from home visit pornographic websites, according to new figures.

Around 3.8 million home users visited an adult site in June, said internet monitoring company NetValue.

It found that 3,879 of the 9,411 websites visited in the month were pornographic, with Britons spending around 45 minutes a month looking at adult material.

The worst offenders were students who account for nearly a quarter of all visits to pornographic sites.

Within Europe, only Germans had a greater appetite for pornography than Britons.

More than 5.3 million Germans visited an adult site in June, spending far more time on these types of websites than any other European nationality.

But Spain has the greatest proportion of visitors to adult sites, with 40% of home net users looking at porn.

"Pornography has become a lucrative online business, with many companies now recognising it as a valuable additional revenue stream," said NetValue's Alki Manias.

"And this would seem to be a stable business area. The popularity of online pornography continues unchecked."

Experts say that although there seems to be a bottomless appetite for online porn, few people are prepared to pay for it, especially since so much of it is available for free.

The downturn on the dotcom economy is making matters worse.

"A lot of our membership comes from people with fast internet connections, and a lot of dotcom people got laid off," Penthouse.com's Van der Leun told the Online Journalism Review last month.

"In this economic climate people look to try to save discretionary purchases."

"We're not recession-proof, but we're highly recession-resistant."

Some experts are concerned that more and more people were becoming addicted to sex on the internet.

Last year, psychologists warned that online sex addiction was creating a dangerous new compulsion affecting everyone from housewives to gay men and corporate executives.

Of the sample of 5,000 people questioned by NetValue, students were the most likely to click on to porn, making up 23.2%.

They were followed by manual workers, 15%, with professionals close behind at 12.8%.