An unidentified disease has killed 60 young children in Cambodia in three months, the World Health Organization said today as it raced to identify the cause.

"The number of deaths reported to WHO is 60 cases and they have all been in young children," said Dr Nima Asgari, a public health specialist for the UN body in Cambodia, adding that the first casualties were reported in April.

The WHO is currently working with the Cambodian Ministry of Health "to identify the cause and the route of spread of this disease", he said.

With the investigation still at an early stage, Asgari said it was difficult to specify the symptoms, which "include high fever and severe chest disease symptoms, plus in some children there were signs of neurological involvement".

There have been 61 reported cases so far, Asgari said, with just one patient surviving. The victims, all aged seven and under, were admitted to hospitals in the capital Phnom Penh and the northwestern tourist hub of Siem Reap.

In separate comments sent to AFP, the WHO said there were no signs yet of contagion.

"To date, there is no report of any staff or any neighbouring patients to the cases at the hospitals becoming sick with similar symptoms," it said.

Asgari confirmed there was "no cluster of the cases yet" but said the high mortality rate in such a short space of time was worrisome.

"WHO is always concerned about a disease which causes death in such high numbers of children," he told AFP.

Cambodian health ministry officials were not immediately available for comment.