More than a third of all web content last year consisted of pornography – more by far than any other category, according to the latest survey by IT security specialist Optenet.

The proportion was actually a one per cent down on the 36 per cent found in a similar 2006 survey, but as the number of sites increased to 155 million that represents an increase in the amount of pornographic content.

Ecommerce accounted for nearly 11 per cent of pages, with travel and adverts each accounting for around seven per cent.

Forums accounted for 7.3 per cent, education for 2.09 per cent just ahead of music at 1.84 per cent.

Some of the smaller categories showed alarming increases: child pornography rose by 18.4 per cent; 470 per cent for sites described as "pro anorexia and bulimia"; 70 per cent for those with violent content; and 70 per cent promoting racism. However, these represented only a small fraction of pages over a period in which the number of websites roughly doubled.