The fourth sexual orientation: One per cent of the population now considers themselves asexual

Leading academic says sexualisation of our culture has turned some into 'asexuals' with no feelings of attraction

Fourth orientation: Experts believe up to 70 million people worldwide have no feelings of sexual attraction at all

Around one per cent of the world's population are 'asexuals' who feel no sexual attraction at all, experts have claimed.

A leading academic has suggested that the sexualisation of our culture has turned people off sexual feelings, to the extent that millions do not have physical attraction to others at all.

Claims that one per cent of the world's population are asexual would mean that 70 million people on Earth feel no sexual attraction.

A book to be published next month even suggests that the growing number of asexuals should be classed as a 'fourth sexual orientation'.

Professor Anthony Bogaert believes that asexuals are 'under-studied' and that they can feel excluded from our 'very sexualised culture'.

Experts say a certain number of asexuals may have always existed but are only now starting to 'come out' as society becomes more liberal.

Professor Bogaert said society can place expectations on both sexual and asexual people.

He defines asexuality as a complete lack of sexual attraction.

Prof Bogaert, an associate professor at Brock University in Canada, said: 'There are two forms: people who have some level of sex drive, but don't direct this drive toward others (so they may masturbate); and other people who have no sex drive whatsoever.'

In 2004, Prof Bogaert analysed the responses of 18,000 people in the UK to a 1994 survey on sexual attraction.

He found that one per cent agreed with the statement: 'I have never felt sexually attracted to anyone at all.'

Claim: Professor Anthony Bogaert believes that asexuals are 'under-studied'

His book to be published next month, Understanding Asexuality, analyses asexuality further, arguing that greater numbers of people now consider themselves 'asexual'.

Joshua Hatton, 23, a language student from Birmingham, told the Independent on Sunday: 'Three years ago, I came across asexuality – it explained everything.

'I no longer had to lie to myself. Young men are expected to have some sort of casual sex; it's all around. Now I feel more comfortable.'

Some asexuals may have extremely low sex drives but others have normal sex drives and are simply not attracted to others, according to a previous New Scientist report.