More than 15 per cent of hospitals and long-term medical care facilities across Japan have recorded cases of sexual assault or abuse of patients, according to a new government report, as concerns mount that the actual figures may be higher.

The Children and Families Agency released the results of the survey – the first of its kind – on Tuesday, with 1,113 institutions of the 5,000 invited to take part providing responses.

Many of the incidents involved medical staff in psychiatry and psychosomatic departments at hospitals, or within internal medical department.

Most – or 66.7 per cent – of the individuals who reported sexual abuse were aged between 19 and 39. Only 3.3 per cent were from 12 to 18.

The numbers for the younger age group looked questionable, said Yoko Tsukamoto, a professor at the Health Sciences University of Hokkaido.