Orphans and children separated from their parents are forced to live alongside strangers in crowded, makeshift shelters, often in dark areas with little supervision.

'We are really concerned about the risk of exploitation and sexual abuse,' said Ms Anne-Claire Dufay, chief of Unicef's child protection section in Myanmar.

She said there had been one report of the attempted trafficking of a teenage storm survivor in Yangon, but no confirmed reports of sexual abuse so far.

Similar concerns were expressed following the 2004 tsunami, but little evidence of such problems emerged.

Unicef estimates that a third of those killed in the devastation following Cyclone Nargis were children, based largely on population data from the affected areas. 'Our figures in the camps show a lot of adults, but very few children and very few elderly,' said Care Australia's country director in Myanmar, Mr Brian Agland.

'In one village there were 500 survivors and they were all adults. So that's the kind of despair people are living with, wondering where their children are.'

In just one township, Unicef said it is trying to identify the parents of 24 children sheltering with strangers.

Many children will also find it difficult to return to school. Unicef says 3,000 schools were wiped out by the cyclone, leaving 500,000 children without classrooms as holidays are set to end early next month.

The United Nations and several non-governmental organisations have been setting up scores of youth centres where the young can talk about their concerns, play games, sing and study.

'It helps these children go through the process of grief and shock more quickly,' said Ms Laura Blank, a spokesman for World Vision, which is setting up 37 centres to serve up to 3,700 youngsters in and around Yangon.

But for now the greatest risk to children is infectious diseases such as cholera, diarrhoea, dysentery, dengue fever and malaria caused by flooding and a lack of clean water, says Unicef.

ASSOCIATED PRESS, AGENCE FRANCE-PRESSE