Young Japanese men are losing interest in sex, according to a study commissioned by the government, in a further warning sign for a nation notorious for its low birth rate, according to a doctor.

The survey also found that more than 40 per cent of married people said they have not had sex in the past month, said Kunio Kitamura, head of the clinic of the Japan Family Planning Association, who took part in the survey.

“This is directly linked with falling birth rate. Policy actions are necessary,” said Dr Kitamura.

The data confirmed a wider social belief that younger men are becoming “herbivorous”, a label attached to passive men who do not actively seek women and sex.

The latest biennial survey found that 36.1 per cent of Japanese males between the ages of 16 and 19 said they had no interest or even despised sex, a jump from 17.5 per cent in the 2008 study. Compounding the issue was data that showed 59 per cent of girls in the same age group felt the same way, up 12 percentage points from 2008.

The data is a worry for a government aiming to encourage couples to have children to reverse a falling birth rate and avert a potential economic calamity.

Japan’s total fertility rate in 2009 was estimated by the government at 1.37 births per woman, one of the world’s lowest, compared with 2.06 in the US and 1.97 in France. The trend has been largely blamed on a widespread belief, especially in rural Japan, that women who give birth should quit their jobs, amid shortages of childcare centres and other systemic factors. Japan’s population has already started to decline as younger people delay starting a family due to the perceived burden on their finances, lifestyles and careers.A growing population of elderly, known for their longevity, is meanwhile overwhelming a welfare system that is decreasingly supported by a shrinking workforce, meaning that tax revenue is declining.

Collectively, the survey found all age categories showed a general lack of interest toward sex, except for men in their 30-34 years of age with just 5.8 per cent of these respondents not interested, as opposed to 8.3 per cent in 2008.